WO1998015095A1

WO1998015095A1 - Structure and method for controlling multiple customer premises equipments on a subscriber's telephone line

Info

Publication number: WO1998015095A1
Application number: PCT/US1997/017307
Authority: WO
Inventors: Richard I. Leggitt; Steven L. Landry; Ron Anglikowski; Harry W. Lewis; Craig W. Hackerd
Original assignee: Cidco Incorporated
Priority date: 1996-10-03
Filing date: 1997-10-01
Publication date: 1998-04-09
Also published as: AU4653197A

Abstract

A structure and method of controlling a plurality of customer premises equipments (CPEs) coupled to a single premises telephone line (10). The CPEs can be Type III GMEC CPE (1), Type II Universal GMEC CPE (2), and/or Type II Satellite GMEC CPE (3). Each of the CPEs includes a signal generator and a signal detector whch allows the CPEs to communicate using out-of-band signalling protocol. By communicating in this manner, the operation of the plurality of CPEs can be coordinated to implement various functions, including master/slave arbritation, multiple extension capability, synchronized flash, remote call record management, and management of shared resources.

Description

STRUCTURE AND METHOD FOR CONTROLLING MULTIPLE CUSTOMER PREMISES EQUIPMENTS ON A SUBSCRIBER'S TELEPHONE LINE

BACKGROUND OF THE INVENTION Field of Invention

The present invention relates to a subscriber telephone system having multiple customer premises equipments (CPEs) connected to a single telephone line. More specifically, the present invention relates to a method and structure for controlling multiple Type II and/or Type III CPEs on a single telephone line.

Description of Related Art Caller-ID capable CPEs, which are connected to a customer's telephone line, and either may or may not function as a telephone, can be generally classified as one of three general "Types". A Type I CPE is a device which is designed to receive on-hook caller identification (CID) information and voice message waiting indicator (VMWI) transmission. A Type I CPE monitors the telephone line to determine when a ring signal is received from the central office. When a ring signal is detected, the Type I CPE monitors the telephone line for caller identification (CID) information which is transmitted between the first and second ring signals. Upon receiving the CID information, the Type I CPE decodes, stores and displays the CID information. Type I CPEs are described in more detail in Bellcore document number TR-NWT-00030.

Type II CPEs are adapted for use in a telephone system which implements caller identification with call waiting (CIDCW). In addition to the conventional Type I functionalities, each Type II CPE includes circuitry for detecting a CPE alerting signal (CAS) tone transmitted by the telephone operating company's central office during a call waiting condition, when the CPE is in an off-hook condition. Upon detecting a CAS tone, a Type II CPE will typically generate a DTMF "D" acknowledge signal, which is transmitted to the central office. Upon receiving the acknowledge signal, the central office transmits CID information, which is received and displayed by the Type II CPE. Type II CPEs therefore allow a customer who is currently talking with a second party to receive CID information from a call waited third party. Type II CPEs are described in more detail in Bellcore document number SR-TSV-002476. Problems can exist when more than one Type II CPE is off-hook when a third party call is received, and each of the off-hook Type II CPEs generates an acknowledge signal in response to a received CAS tone. Simultaneously generating acknowledge signals with multiple CPEs can result in mis-operation.

Type III CPEs are adapted for use in a telephone system which implements the Analog Data Services Interface (ADSI) protocol. Type III CPEs include the previously described Type I and Type II CPE functionalities. Thus, a Type III CPE includes circuitry for detecting a CAS tone transmitted by either the central office or an ADSI server. When a Type III CPE detects a CAS tone, the Type III CPE generates an acknowledge signal in a similar manner as a Type II CPE. However, the Type III CPE generates a DTMF "A" acknowledge signal, rather than a DTMF "D" acknowledge signal. In response to the DTMF "A" acknowledge signal, the central office can initiate a CIDCW session or an ADSI server can initiate an ADSI session. Type III CPEs are described in more detail in Bellcore document number TR-NWT-001273. According to this standard, a Type III CPE cannot engage in an ADSI session if any other CPE on the same telephone line is in an off-hook condition. It would therefore be desirable to have a method and structure for allowing multiple Type II and/or multiple Type III CPEs to be operably connected to a single telephone line, wherein these Type II and/or Type III CPEs will reliably respond to received CAS tones when more than one of these CPEs are in an off- hook condition. In addition, each Type I, Type II and Type III CPE typically maintains a list of call records, wherein each call record includes the CID information from a received call. Maintenance of the call record list at each CPE requires the customer to physically move to the location of each individual CPE. For example, to delete a stored call record from multiple CPEs connected to a common telephone line, the user must move to each CPE and manually delete the call record on each individual CPE. This is inconvenient for the customer. In addition, confusion can easily arise as to which call records are new and which call records have been previously reviewed. It would therefore be desirable to have a method and system for conveniently managing the call record lists stored by a plurality of CPEs which are coupled to a single telephone line.

Furthermore, when two or more CPEs are in an off-hook condition, certain conventional functionalities of the CPEs may not work. For example, when two CPEs are off-hook, a hook flash operation performed by one of the off-hook CPEs will fail to impose a hook flash condition on the telephone line because the other off-hook CPE will prevent the line from going to an on-hook voltage state. It would therefore be desirable to be able to perform conventional operations, such as a hook flash operation, when two or more CPEs connected to a single telephone line are in an off-hook condition. In addition, when there are a plurality of CPEs connected to a single telephone line, one of these CPEs may be capable of implementing a special function which the other CPEs are incapable of performing. It would be desirable to have a method of sharing the resource which implements this special function among all of the CPEs connected to the telephone line.

SUMMARY

Accordingly, the present invention provides a structure and method of controlling a plurality of customer premises equipments (CPEs) coupled to a single telephone line within a customer's premises. Each of the CPEs includes a signal generator and a signal detector which allows the CPEs to communicate using an out-of-band signalling protocol. Because this out-of-band signalling protocol enables a generalized multiple extension capability (GMEC), such CPEs are hereinafter referred to as GMEC CPEs.

Using the out-of-band signalling protocol, the operation of the GMEC CPEs can be coordinated to implement various functionalities, including master/slave arbitration, multiple extension capability, synchronized flash, remote call record management and management of shared resources.

In master/slave arbitration, each GMEC CPE assigns itself a priority code based on the type and present condition of the GMEC CPE (e.g., on-hook condition, off-hook condition). The GMEC CPE with the highest priority code becomes the master GMEC CPE. The master GMEC CPE periodically transmits an out-of-band ITM (I'm The Master) instruction signal to the other CPEs connected to the telephone line. The ITM instruction includes the priority code of the master GMEC CPE. When another GMEC CPE determines that its priority code has exceeded the priority code of the master GMEC CPE, the GMEC CPE having the higher priority code begins to periodically transmit an ITM instruction which includes this higher priority code. The master GMEC CPE detects this higher priority code and ceases transmitting its ITM instruction. In this manner, the GMEC CPE having the highest priority code automatically becomes the master GMEC CPE.

The master GMEC CPE is the only GMEC CPE which is allowed to respond to CAS tones detected on the telephone line. As a result, there is no signal distortion created by multiple GMEC CPEs attempting to respond to a received CAS tone. Off-hook Type III GMEC CPEs are assigned the highest priority code, thereby allowing the off-hook Type III GMEC CPE to generate an appropriate acknowledge signal in response to a detected CAS tone.

Each GMEC CPE can include one or more keys which enable the user to initiate functions using the GMEC protocol. These functions include (1) dialing a displayed telephone number from any GMEC CPE, (2) performing a synchronized hook flash operation when more than one GMEC CPE is in an off-hook condition, (3) deleting one or more call records simultaneously from all GMEC CPEs, (4) marking as reviewed one or more call records simultaneously on all GMEC CPEs, (5) disconnecting other GMEC CPES from the telephone line to initiate a private call, and (6) turning off the message waiting indicator simultaneously on all GMEC CPEs.

The GMEC protocol also enables the use of a Type II satellite GMEC CPE which does not include conventional CAS tone detection circuitry, DTMF signal generation circuitry, ring signal detection circuitry or FSK data reception circuitry. The Type II satellite GMEC CPE is informed of the presence of ring signals, CAS tones, and CID information by out-of-band signals transmitted by the master GMEC CPE. Eliminating circuitry which implements these functions from the Type II satellite GMEC CPE advantageously reduces the cost of the Type II satellite GMEC CPE with respect to the cost of the other GMEC CPEs.

The present invention will be more fully understood in light of the following detailed description taken together with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a block diagram of a plurality of CPEs coupled to a telephone line; Fig. 2 is a block diagram of a Type II GMEC CPE (and a Type III GMEC CPE) in accordance with one embodiment of the invention; and

Fig. 3 is a block diagram of Type II satellite GMEC CPE in accordance with one embodiment of the invention.

DETAILED DESCRIPTION Fig. 1 is a block diagram illustrating a plurality of CPEs 1-3 coupled to a customer's telephone line 10 in accordance with one embodiment of the invention. As described in more detail below, each of CPEs 1 -3 has a multiple extension capability. The multiple extension capabilities of CPEs 1 -3 represent an extension of the multiple extension capabilities described in commonly owned U.S. Patent Applications Serial Nos. 08/388,108 and 08/431,172, which are hereby incorporated by reference in their entirety. In accordance with the present invention, each of the CPEs 1-3 also includes a dedicated signal generator and a dedicated signal detector for enabling communication between CPEs 1-3. CPEs 1- 3 communicate via these signal generators and signals detectors using a generalized multiple extension capability (GMEC) protocol which is also described in more detail below. CPEs which are capable of communicating with the GMEC protocol are hereinafter referred to as GMEC CPEs.

GMEC CPEs can be generally classified as Type III GMEC CPEs (e.g., CPE 1), Type II GMEC CPEs (e.g., CPEs 2 and 3), and Type I GMEC CPEs (not shown). Type III GMEC CPEs include all of the functionalities of a conventional Type III CPE, plus the additional functionalities enabled by the GMEC protocol, as described in more detail below. Similarly, Type I and Type II GMEC CPEs include all of the functionalities of a conventional Type I and Type II CPEs, respectively, plus the additional functionalities enabled by the GMEC protocol, as described in more detail below. Type II GMEC CPEs can further be classified as Type II full-feature GMEC CPEs (e.g., CPE 2) and Type II satellite GMEC CPEs (e.g., CPE 3). For reasons described in more detail below, Type II satellite GMEC CPEs can only be used in the presence of a Type III GMEC CPE or a Type II full- feature GMEC CPE due to their lack of any CAS tone detection circuitry and their "slaved" status to a designated Type II full featured GMEC CPE or Type III

GMEC CPE operating as a master. Each of these GMEC CPEs 1-3 is described in more detail below.

Fig. 2 is a block diagram of Type II full-feature GMEC CPE 2. CPE 2 includes signal detector 201, signal generator 202, telephone circuit 205, line protection circuit 210, relay 215, ring detector circuit 220, first micro-controller

230, data reception circuit 240, display 250, keys 255, line-in-use (LIU) circuit 260, polarity guard circuit 265, second micro-controller 270, CAS tone filters 275, DTMF signal generator 280, line hold and signal injection circuit 285, phone line switch 290 and power supply 295. Although the present embodiment is described as having a first micro-controller 230 and a second micro-controller 270, it is understood that in other embodiments, these micro-controllers can be implemented using a single micro-controller.

CPE 2 is coupled to the telephone line 10 via line protection circuit 210 and relay 215. Line protection circuit 210 protects CPE 2 against over voltage and over current conditions on telephone line 10.

Line-in-use circuit (LIU) 260 is coupled to the telephone line 10 through polarity guard 265. Polarity guard 265 protects against polarity reversal of the tip and ring lines of telephone line 10 and provides the voltage on telephone line 10 to LIU circuit 260. LIU circuit 260 detects whether any CPE connected to telephone line 10 is in use (i.e., off-hook) by monitoring the voltage on telephone line 10. LIU circuit 260 asserts an OFF HOOK signal when the change in voltage on telephone line 10 indicates that line 10 is in an off-hook condition. The OFF_HOOK signal is provided to first micro-controller 230 and second microcontroller 270, thereby enabling first micro-controller 230 and second micro- controller 270 to determine in real time when telephone line 10 is in an on-hook or off-hook condition.

Ring detector circuit 220, which is coupled to telephone line 10 through line protection circuit 210, asserts a RING signal on line 221 when a ring signal is detected on telephone line 10. First micro-controller 230 is coupled to receive the RING signal. In response to the RING signal, first micro-controller 230 sets up CPE 2 to receive the CID information for an on-hook incoming call.

A data reception circuit 240 is also coupled to telephone line 10 through line protection circuit 210. Data reception circuit 240 receives the CID information received from the central office on telephone line 10. The central office sends the caller information in a frequency shift keying ("FSK") format. Data reception circuit 240 decodes the FSK signal and provides the CID information to first micro-controller 230 as a digital signal RxD. Data reception circuit 240 also provides a -CD signal to first micro-controller 230 when data reception circuit 240 detects the carrier signal for the FSK signal. In response to the RxD and -CD signals, first micro-controller 230, causes display 250 to display the received CID information.

Data reception circuit 240 also provides a TONE OUT signal, which is representative of the signals on telephone line 10, to CAS tone filter circuit 275. CAS tone filter 275 passes signals which exhibit the frequencies associated with a CAS tone (e.g., 2130 Hz and 2750 Hz). The signals passed by CAS tone filter 275 are provided to second micro-controller 270. In response, second micro-controller 270 determines whether a valid CAS tone exists on telephone line 10 using a tone detection method such as that described in commonly owned U.S. Patent Application Serial No. 08/387,666, which is hereby incorporated by reference in its entirety, or other CAS tone detection means. When a valid CAS tone is detected, second micro-controller 270 asserts a CAS_DET signal, which is transmitted to first micro-controller 230. It is recognized and deemed within the scope of this invention that the functions and operations of microcontrollers 230 and 270 may be combined into a single microcontroller. However, for the purposes of describing the operation of the present invention, two separate microcontrollers, as described, will continue to be used.

Second micro-controller 270 is also coupled to relay 215. Second microcontroller 270 controls the operation of relay 215 to connect or disconnect telephone circuit 205 from telephone line 10. Upon detecting a valid CAS tone, second micro-controller 270 transmits a RELAY_OUT signal which causes relay 215 to disconnect telephone circuit 205 from telephone line 10.

Second micro-controller 270 is also coupled to receive a M/S signal from first micro-controller 230. As described in more detail below, first micro- controller 230 generates the M/S signal in response to out-of-band signals received by signal detector 201. The state of the M/S signal instructs second microcontroller 270 to operate in a master mode or a slave mode. In slave mode, second micro-controller 270 inhibits DTMF generator 280 from generating an acknowledge signal (i.e., CPE 2 does not acknowledge a detected CAS tone when in slave mode). In master mode, after receiving a valid CAS tone and actuating relay 215, second micro-controller 270 monitors the signal provided by LIU circuit 260 to determine whether telephone line 10 is on-hook. If telephone line 10 is on-hook, second micro-controller 270 transmits a TERMINATEJLINE signal to phone line switch 290 which causes phone line switch 290 and line hold circuit 285 to couple an impedance equivalent to the impedance of a standard off-hook telephone to the telephone line 10, thereby placing telephone line 10 in an off-hook condition. Second micro-controller 270 then activates DTMF generator 280, thereby transmitting a DTMF "D" acknowledge signal to the central office on telephone line 10. In response to this acknowledge signal, the central office sends the CID information. Data reception circuit 240 receives this CID information. First micro-controller 230 stores the received CID information, and causes the CID information to be shown on display 250.

Power supply circuit 295 directly or indirectly supplies the power and ground potentials to the circuitry of CPE 2. Key circuit 255 is coupled to first micro-controller 230 to control the operation of CPE 2 via user initiated input signals.

The previously described elements and operation of CPE 2 are described in more detail in commonly owned, co-pending U.S. Patent Application Serial Nos. 08/343,306 and 08/387,666, which are hereby incorporated by reference in their entirety.

CPE 2 also includes signal detector 201 and signal generator 202. Signal generator 202 is connected between first micro-controller 230 and telephone line 10 (through polarity guard 265). Signal generator 202 transmits coded signals to telephone line 10 in response to instructions received from first micro-controller 230. The instructions provided by first micro-controller 230 can be generated in response to signals received from signal detector 201, or in response to user input signals received from keys 255. The coded signals generated by signal generator 202 are broadcast to all of the GMEC CPEs connected to telephone line 10. In this manner, CPE 2 can communicate information or instructions to other GMEC CPEs connected to telephone line 10.

The coded signals generated by signal generator 202 are transmitted using a carrier signal having a frequency which exists outside of the range of frequencies used for voice and modem communications while meeting the FCC regulations for telephone line signals. In the described embodiment, the coded signals are transmitted in an FSK format which uses a carrier signal having a frequency of 455 kHz (a typical intermediate frequency used in many consumer radios), but of course, other frequencies can be used. In another embodiment, the coded signals are sent using a pulse width modulation (P WM) format. In yet other embodiments, the coded signals can be sent through AC power lines or through free space (rather than through phone line 10) using radio frequency (RF) infra-red (IR) signals through conventional transmission methods well known to those skilled in the art. Hereinafter, the coded signals transmitted between GMEC CPEs are collectively referred to as "out-of-band" signals.

Signal detector 201 is connected to phone line 10 through line protection circuit 210. Signal detector 201 monitors telephone line 10 for out-of-band signals which are transmitted by the signal generators located in other GMEC CPEs. Signal detector 201 converts the out-of-band signals to coded digital signals which are provided to first micro-controller 230. In this manner, CPE 3 can receive information or instructions from other CPEs connected to telephone line 10.

In one embodiment, all of the circuitry of CPE 2 is integrated within a single telephone housing. In such an embodiment, CPE 2 is capable of monitoring the status of the hook switch (not shown) located within telephone circuit 205 to determine whether or not associated telephone circuit 205 is in an on-hook or off- hook condition. Such a CPE 2 is hereinafter referred to as a Type II full-feature integrated CPE (ICPE).

Alternatively, the telephone circuit 205 is located in a telephone housing and the remaining circuitry of CPE 2 is located in a separate adjunct housing. In such an embodiment, the circuitry of CPE 2 which is located in the adjunct housing is typically unaware of whether or not its associated telephone circuit 205 is in an on-hook or off-hook condition. As a result, the adjunct is given the lowest master priority code, as described in detail below, to compensate for the adjunct's inability to determine the hook switch status of its associated telephone circuit, and allow the adjunct to function in accordance with the present invention without adversely affecting the overall operation. Such a CPE 2 is hereinafter referred to as a Type II full-feature adjunct with an associated telephone.

The block diagram of Fig. 2 is also representative of the circuitry present within Type III GMEC CPE 1. However, in Type III GMEC CPE 1, the first micro-controller 230 is programmed to allow Type II GMEC CPE 1 to engage in ADSI sessions in addition to CID and CIDCW sessions. To help accomplish this, second micro-controller 270 is capable of causing DTMF generator 280 to generate two types of acknowledge signal, either a DTMF "A" acknowledge signal for an ADSI session or a DTMF "D" acknowledge signal for a CIDCW session. The operation of Type III GMEC CPE 1 is described in more detail below. In the described embodiment, Type III GMEC CPE 1 is integrated into a single telephone housing, such that CPE 1 can determine whether or not its associated telephone circuit 205 is in an off-hook or on-hook condition.

Fig. 3 is a block diagram of Type II satellite GMEC CPE 3. Certain elements of Type II satellite GMEC CPE 3 are similar to elements previously described in connection with Type II full-feature GMEC CPE 2 (Fig. 2). Consequently, similar elements are labeled with similar reference numbers in Fig. 3. Type II satellite GMEC CPE 3 includes signal detector 201, signal generator 202, telephone circuit 205, line protection circuit 210, relay 215, micro-controller 230, display 250, keys 255, LIU circuit 260, polarity guard 265 and power supply

295. It is important to note that satellite GMEC CPE 3 does not include ring detector circuit 220, second micro-controller 270, CAS tone filters 275, DTMF signal generator 280, line hold circuit 285 and line switch 290, as previously discussed in connection with full-feature GMEC CPE 2. The elimination of these elements from satellite GMEC CPE 3 prevents CPE 3 from operating in a master mode. The elimination of these elements also prevents satellite GMEC CPE 3 from operating in a stand-alone configuration. That is, the proper operation of satellite GMEC CPE 3 requires the presence of a Type III GMEC CPE or a Type II full-feature GMEC CPE which is operating in the master mode. Satellite GMEC CPE 3 is able to operate in a slave mode in response to out-of-band signals generated by the above mentioned GMEC CPEs 1 -2 and received by signal detector 201 of the satellite GMEC CPE 3. As described in more detail below, the out-of-band signals received by signal detector 201 provide GMEC CPE 3 with information concerning ring signal detection, CAS tone detection, and CID information. In response to these out-of-band signals, satellite GMEC CPE 3 is able to receive, store and display CID information. In addition, satellite GMEC CPE 3 is able to communicate with other GMEC CPEs using the GMEC protocol described in more detail below.

By eliminating ring detector circuit 220, second micro-controller 270, CAS tone filters 275, DTMF signal generator 280, line hold circuit 285 and line switch 290 in satellite GMEC CPE 3, the cost associated with making satellite GMEC CPE 3 is greatly reduced when compared with the cost of making full-feature GMEC CPE 2. In an alternative embodiment, the memory capability is removed from the micro-controller 230 of satellite GMEC CPE 3, thereby further reducing the cost of this CPE 3. In the described embodiment, Type II satellite GMEC CPE 3 is implemented with telephone circuit 205 located in a telephone housing and the remaining elements located in an adjunct housing. As a result, Type II satellite GMEC CPE 3 is incapable of determining the on-hook/off-hook status of its associated telephone circuit. However, unlike the previously described Type II GMEC adjunct, the Type II satellite GMEC CPE 3 is incapable of becoming the master GMEC CPE and is therefore not assigned a master priority code. As described in more detail below, the inability of a Type II satellite GMEC CPE to determine the hook switch status of its associated telephone circuit does not affect the ability of the Type II satellite GMEC CPE to implement various GMEC functionalities. In another embodiment, all of the elements of Type II satellite

11 GMEC CPE 3 are integrated in a single telephone housing, such that GMEC CPE 3 is capable of detecting the hook switch status of its associated telephone circuit 205.

GMEC CPEs 1-3 communicate with each another by the out-of-band signals using a GMEC protocol. This GMEC protocol enables multiple GMEC CPEs 1-3 to be operably connected to telephone line 10. Although Fig. 1 illustrates only one Type III GMEC CPE 1, one Type II full-feature GMEC CPE 2 and one TYPE II satellite GMEC CPE 3 coupled to telephone line 10, it is understood that any number of each of these GMEC CPEs 1-3 can be operably connected to telephone line 10 using the GMEC protocol. Table 1 lists the instructions used in the GMEC protocol in accordance with one embodiment of the invention. Table 2 indicates the GMEC CPEs which generate and receive the GMEC instructions listed in Table 1.

Table 1 - GMEC INSTRUCTIONS

1. ITM [priority] 12. DELETE [hash]

2. BREAK [duration] 13. DELETE_ALL

3. CAS 14. REVIEWED [hash]

4. RING 15. REVIEW_ALL 5. CID 16. DIAL [number]

6. ERROR 17. TEST

7. MW_ON 18. PRIVATE

8. MW OFF 19. PUBLIC

9. IMOFF 20. RECORD[index][hash][data] 10. ITSfcalls] 21. NO_RECORD [index]

11. REQUEST[index] TABLE 2

Instructions broadcast by a Master GMEC CPE ITM, CAS, RING, CID, to other GMEC CPEs MW_ON, MW_OFF

Instructions broadcast by a Server GMEC CPE ITS, RECORD, to non-Server GMEC CPEs NO_RECORD

Instructions broadcast by a non-Master GMEC IMOFF, DIAL CPE to a Master GMEC CPE

Instructions broadcast by a non-Server GMEC REQUEST CPE to a Server GMEC CPE

Instructions broadcast by any GMEC CPE to any BREAK, DELETE, other GMEC CPE DELETE ALL, REVIEWED, REVIEW ALL, TEST, PRIVATE, PUBLIC

Each of the GMEC instructions listed above is encoded as using an appropriate number of bits, depending on the programming convention selected, such as a 5-bit word. Conventional encryption, validation and error correction techniques are used to transmit and receive the GMEC instructions. Other embodiments may utilize additional GMEC instructions related to future functionalities, depending upon the particular operational requirements, thereby requiring additional bits to encode all of the GMEC instructions. In the described embodiment, for example, the GMEC instructions are transmitted over the tip and ring lines (i.e., the shared telephone line connection) using an out-of-band FSK scheme which uses a 450 kHz signal as a first logic level and a 460 kHz signal as a second logic level. While frequencies of 450 kHz and 460 kHz were chosen for this particular embodiment, in other embodiment, other frequencies can be used. In this particular embodiment, the signal generator within each GMEC CPE is designed to transmit such FSK signals. Furthermore, the signal detector within each GMEC CPE is designed to detect and decode such FSK signals. In the described embodiment, the medium over which the GMEC instructions and data is transmitted is assumed to be the shared telephone line. However, those skilled in

m the art will recognize that other embodiments could use other transmission channels for communication as previously described.

The GMEC instructions are used to implement the following applications: (1) master/slave arbitration, (2) multiple extension capability, (3) synchronized flash, (4) remote call record management, (5) management of shared resources. These applications are discussed below. In the following discussion, it is assumed that all of the devices coupled to the telephone line 10 are GMEC CPEs, unless otherwise noted.

(1) Master/Slave Arbitration

When multiple GMEC CPEs are connected on a single telephone line, one of the GMEC CPEs is automatically selected to operate in a master mode (i.e., a master GMEC CPE). As previously discussed, a Type II satellite GMEC CPE is not capable of detecting a CAS tone, and is therefore not capable of operating in a master mode. Therefore, the master GMEC CPE is selected from among the Type III GMEC CPEs, the Type II full-feature GMEC ICPES and the Type II full- feature GMEC adjuncts. The master GMEC CPE is the only GMEC CPE which generates an acknowledge signal in response to a CAS tone received from the central office. This prevents the generation of a distorted acknowledge signal resulting from collision, which could otherwise result if a plurality of CPEs simultaneously attempted to respond to a CAS tone.

In one embodiment, the selection of the master GMEC CPE among the other GMEC CPEs coupled to the telephone line is performed as follows. When power is initially supplied to a GMEC CPE (i.e., when the GMEC CPE is plugged in, or when the power is restored after a power outage), the GMEC CPE will display a message which states "PRESS ANY BUTTON". The GMEC CPE will not become activated and therefore operational until the user presses a button on the GMEC CPE. When the user presses a button on the first GMEC CPE which is capable of becoming a master, that GMEC CPE becomes activated and monitors the telephone line to detect the presence of an out-of-band ITM (I'm The Master)

1b instruction. Since none of the other GMEC CPEs capable of becoming the master GMEC CPEs have been activated at this point, a master GMEC CPE has not yet been selected and no such ITM instruction is present on the telephone line. Upon not detecting an ITM instruction for a predetermined time period, the first activated GMEC CPE capable of becoming the master which designates itself as the master GMEC CPE. Upon becoming the master GMEC CPE, this GMEC CPE begins periodically transmitting an out-of-band ITM (I'm The Master) instruction, as previously described, to the telephone line using its associated signal generator. Each ITM instruction includes a priority code which is representative of the status and type of the particular GMEC CPE transmitting the ITM signal. Table 3 lists the priority codes for the GMEC CPEs in accordance with one embodiment of the invention.

Table 3 - Master Priority Codes

GMEC Priority

GMEC CPE CPE Status Code

Type II full-feature adjunct n/a 0

Type II full-feature ICPE on-hook 1

Type III CPE on-hook 2

Type II full-feature ICPE w/shared resource on-hook 3

Type III CPE w/shared resource on-hook 4

Type II full-feature ICPE off-hook 5

Type III CPE off-hook 6

Type III CPE off-hook 7 (After IMOFF)

1 For example, an on-hook Type III GMEC CPE would transmit an ITM instruction which includes a priority code of "2".

As buttons are pressed to activate other GMEC CPEs which are capable of becoming the master GMEC CPE, these newly activated GMEC CPEs monitor the telephone line for the presence of an ITM instruction. Upon receiving the ITM instruction being transmitted by the master GMEC CPE, the activated GMEC CPEs compare the priority code of the master GMEC CPE with their own priority codes. If the priority code of a newly activated GMEC CPE is equal to or lower than the priority code of the current master GMEC CPE, then the newly activated GMEC CPE does nothing to assume mastership. However, if the priority code of the newly activated GMEC CPE is greater than the detected priority code of the master GMEC CPE, then the newly activated GMEC CPE transmits an ITM instruction which includes this higher priority code.

All GMEC CPEs, including the master GMEC CPE, monitor the telephone line to receive ITM instructions transmitted by other GMEC CPEs. Upon receiving an ITM instruction having a higher priority code than its own priority code, the master GMEC CPE will automatically surrender the mastership to the GMEC CPE having the higher priority code by terminating the transmission of its own ITM instruction. A conventional collision algorithm, such as the CSMA CD (carrier sense, multiple access, collision detect) algorithm used in Ethernet applications, is used to ensure that the ITM instructions are transmitted and received reliably.

Each GMEC CPE automatically updates its own priority code and compares this priority code with the priority code of the ITM instruction periodically received from the current master GMEC CPE. As illustrated in Table 3, the priority codes of existing GMEC CPEs change as these GMEC CPEs transition between on-hook and off-hook conditions. As the priority codes change, the master GMEC CPE can change dynamically and automatically during normal operation of the telephone system. If the master GMEC CPE becomes non-operational (e.g., is disconnected), the remaining activated GMEC CPEs detect the absence of the ITM instruction (for a predetermined time period). In response to the detected absence of the ITM instruction, each GMEC CPE periodically transmits an ITM instruction to the telephone line. Each ITM instruction includes the priority code associated with the particular GMEC CPE transmitting the ITM instruction. Each GMEC CPE also monitors the telephone line to receive the ITM instructions transmitted by other GMEC CPEs. Again, a conventional collision algorithm is used to ensure that the ITM instructions are transmitted and received reliably. When a GMEC CPE receives an ITM instruction with a priority code which is greater than or equal to its own priority code, the receiving GMEC CPE stops transmitting its ITM instruction. Eventually, only one GMEC CPE will be periodically transmitting an ITM instruction. This GMEC CPE automatically becomes the master GMEC CPE. In another embodiment, the master GMEC CPE is initially selected without having to press a button to individually activate each GMEC CPE. In this embodiment, each GMEC CPE is pre-programmed to activate itself at a random time after power is supplied to the GMEC CPE. This can be accomplished by including a random number generator having a unique seed value in each GMEC CPE. Such a scheme minimizes the probability that two or more GMEC CPEs will be activated simultaneously, thereby disrupting the collision algorithm.

The ITM priority codes are selected to ensure optimal selection of the master GMEC CPE. This statement is best explained by the following examples. For example, assume that the GMEC CPEs connected to a telephone line include a Type II full-feature GMEC adjunct, a Type II full-feature GMEC ICPE and a Type III GMEC CPE. When all of these GMEC CPEs are on-hook, the Type III CPE (ITM priority code = 2) becomes the master GMEC CPE. The Type III CPE is given priority over the Type II full-feature GMEC ICPE because the tone detection circuitry present in Type III CPEs is nominally better than the tone detection circuitry present in Type II CPEs. Otherwise, an on-hook Type II GMEC

1ϊ CPE could be given the same ITM priority code as an on-hook Type III GMEC CPE.

If either the on-hook Type III GMEC CPE or the on-hook Type II full- feature GMEC ICPE includes a resource which can be shared, then the on-hook GMEC CPE having this resource is given a higher ITM priority code (i.e., 3 or 4) than any other on-hook GMEC CPE. One example of a resource which can be shared is a "refuse blocked calls" functionality. A "refuse blocked calls" functionality causes the GMEC CPE to prevent the connection of a telephone call placed by a calling party who is blocking the transmission of his/her CID information. If only the Type II full-feature GMEC ICPE includes the "refuse blocked calls" functionality, then this GMEC ICPE becomes the master GMEC CPE during on-hook conditions by virtue of its higher priority code (e.g., 3). As a result, when a call is received during an on-hook condition, the Type II full-feature GMEC ICPE, being the master GMEC CPE, responds with its "refuse blocked calls" functionality, if the calling party has blocked transmission of his/her CID information. As a result, the entire telephone system obtains the "refuse blocked calls" functionality, even though only one GMEC CPE includes this functionality. In this manner, the resource is shared among all GMEC CPEs.

If the Type II full-feature GMEC ICPE subsequently goes off-hook, then this off-hook Type II full-feature GMEC CPE obtains a higher ITM priority code

(i.e., 5) than any on-hook GMEC CPE. The off-hook Type II full-feature GMEC ICPE thereby becomes the master GMEC CPE via transmission of an ITM instruction. Upon receipt of a CAS tone, the off-hook Type II full-feature GMEC ICPE will respond with a DTMF "D" acknowledge signal, which is the appropriate acknowledge signal for all Type II CPEs.

An off-hook Type III GMEC CPE obtains a higher ITM priority code (i.e., 6) than any other GMEC CPE. An off-hook Type III GMEC CPE becomes the master GMEC CPE via transmission of an ITM instruction having a priority code of 6. Upon receiving the priority 6 ITM instruction transmitted by the off-hook Type III GMEC CPE, each of the other GMEC CPEs capable of detecting the on-

1^*1 hook/off-hook status of its associated telephone circuit hook switch monitors its associated telephone circuit to determine if that associated telephone circuit is, or has gone, off-hook. If a GMEC CPE determines that its associated telephone is in an off-hook condition in the presence of a priority 6 ITM instruction, then that GMEC CPE broadcasts an out-of-band IMOFF (I'm off-hook) instruction on the telephone line. The off-hook Type III master GMEC CPE detects this IMOFF instruction, and in response, spontaneously upgrades its ITM priority code to 7. While having an ITM priority code of 7, the off-hook Type III master GMEC CPE will acknowledge CAS tones (if at all) with a DTMF "D" signal. This prevents the off-hook Type III master GMEC CPE from initiating an ADSI session when another GMEC CPE is off-hook (because an ADSI session requires a DTMF "A" signal). If the off-hook Type III master GMEC CPE is currently engaged in an ADSI session, the session is aborted when the ITM priority code becomes 7. A Type III master GMEC CPE having an ITM priority code of 7 periodically drops its ITM priority code to 6. If another GMEC CPE determines that its associated telephone is in an off-hook condition in the presence of this priority 6 ITM instruction, then this GMEC CPE generates another IMOFF instruction. In response to this IMOFF instruction, the Type III master GMEC CPE again upgrades its priority code to 7. If the Type III master GMEC CPE does not detect an IMOFF instruction on the telephone line after dropping its priority code to 6, then the Type III master GMEC CPE remains at an ITM priority code of 6. The Type III master GMEC CPE having an ITM priority code of 6 responds to CAS tones (if at all) with a DTMF "A" acknowledge signal. By transmitting a DTMF "A" acknowledge signal, the off-hook Type III GMEC CPE is able to initiate either an ADSI session or a CIDCW session.

To summarize, if an off-hook GMEC CPE is initially preventing the off- hook Type III GMEC CPE from engaging in an ADSI session, and the off-hook GMEC CPE subsequently goes on-hook, the off-hook Type III GMEC CPE detects this condition, and is subsequently allowed to engage in an ADSI session at this time.

lo Table 4 provides a summary of selected capabilities of Type II and Type III GMEC CPEs.

Table 4

Type III Type II Type II Type II

GMEC CPE GMEC ICPE GMEC Adjunct Sat. GMEC CPE

Can break line YES YES YES YES

Receives CAS YES YES YES NO

Receives in-band FSK YES YES YES NO

Can be Master YES YES YES NO

Detects LIU YES YES YES YES

Detects own LIU YES YES NO NO

(2) Multiple Extension Capability

The master GMEC CPE operates as follows to enable a multiple extension capability.

On-hook operation

If all CPEs are in an on-hook condition, and an incoming call is received, the central office will send CID information in FSK format between the first and second ring signals. The master GMEC CPE detects the ring signal using its associated ring signal detector circuit 220 as shown in Fig. 2. This ring signal is passed to the first micro-controller 230 as a RING signal. Upon detecting the a RING signal, the first micro-controller 230 of master GMEC CPE causes its signal generator 202 to broadcast an out-of-band RING instruction, as previously described herein, on the telephone line. The master GMEC CPE generates a RING instruction for each detected ring signal. In one embodiment, the RING instruction is generated for each detected RING signal until the master detects that the telephone line is in an off-hook condition (using its associated line-in-use circuit 260), or until a predetermined time period elapses without receiving a ring signal. In one embodiment, this predetermined time period is approximately 6 seconds. The RING instructions transmitted by signal generator 202 of the master

GMEC CPE are detected by the signal detector circuits 201 within each of the Type II satellite GMEC CPEs (Fig. 3). In this manner, the satellite GMEC CPEs are informed of ring signals which exist on the telephone line. Upon receiving the first RING instruction, the satellite GMEC CPEs prepare to receive CID information from an out-of-band CID instruction sent by the master GMEC CPE. Between the first and second ring signals, the master GMEC CPE receives and decodes the incoming FSK CID information using the data reception circuit 240 associated with the master GMEC CPE. The first micro-controller 230 within the master GMEC CPE then causes the signal generator 202 within the master GMEC CPE to generate an out-of-band CID instruction which is broadcast to all CPEs connected to the telephone line. The CID instruction is detected by the signal detector 201 in each of the satellite GMEC CPEs connected to the telephone line. The CID instruction includes a data field which includes information which is representative of the CID information transmitted by the central office and received by the master GMEC CPE. This data field typically includes the name and telephone number of the calling party, as well as a time stamp which identifies, to the nearest minute, the time that the call was received. Each satellite GMEC CPE decodes the received out-of-band CID instruction and displays the CID information. Each satellite GMEC CPE also stores the received CID information in a memory within its associated first micro-controller 230. All GMEC CPEs sequentially tag the CID signals received within the same one minute period (as defined by the time stamp of the CID information). This is done by appending a SEQUENCE TAG signal to each call record. The SEQUENCE TAG is incremented by one each time a new call is received during the same one minute period. The SEQUENCE TAG is reset when the one minute period expires. The SEQUENCE TAG signal enables the GMEC CPEs to differentiate between calls received from the same party during the same minute. If the master GMEC CPE does not receive CID information between the first and second ring signals, the master GMEC CPE broadcasts an out-of-band ERROR instruction on telephone line using its signal generator 202. The ERROR instruction informs the satellite GMEC CPEs that a CID signal will not be

ϊl received. As a result, the satellite GMEC CPEs will stop waiting for an out-of- band CID instruction.

The GMEC CPEs which are not satellite GMEC CPEs (i.e., Type III GMEC CPEs and Type II full-feature GMEC CPEs) receive CID information during on-hook conditions in the same manner as a conventional Type I CPE. That is, each of these GMEC CPEs detects the ring signals and CID information using its corresponding ring detector circuit 220 and data reception circuit 240, respectively.

In addition, each non-GMEC CPE coupled to the telephone line receives information during on-hook conditions (if at all) in the same manner as a conventional Type I CPE.

Off-hook Operation

If the central office detects that the telephone line is in an off-hook condition when a party is attempting to call the customer, the central office will transmit a CAS tone on the telephone line. Each of the Type II full-feature GMEC CPEs and the Type III GMEC CPEs (one of which is the master GMEC CPE) detects the presence of the CAS tone using their associated CAS tone filters 275 and second micro-controllers 270 (Fig. 2). Upon detecting the CAS tone, each of the second micro-controllers 270 asserts the RELAY OUT signal, thereby actuating its associated relay 215 to disconnect its associated telephone circuit 205 from the telephone line. Each of the second micro-controllers 270 also informs its associated first micro-controller 230 of the detected CAS tone by asserting the CAS_DET signal. In response, the first micro-controller 230 of the master GMEC CPE causes the signal generator 202 within the master GMEC CPE to broadcast an out-of-band CAS instruction on the telephone line.

Each of the satellite GMEC CPEs receives the CAS instruction with its corresponding signal detector 201 and is thereby informed of the presence of the CAS tone. In response to the CAS instruction, the first micro-controllers 230 within the satellite GMEC CPEs temporarily disconnect their associated telephone

I'b circuits 205 by asserting a RELAY_OUT signal which is applied to relay 215. The satellite GMEC CPEs then await an out-of-band CID instruction or an ERROR instruction as previously described.

After all the GMEC CPEs have had a chance to disconnect their associated telephone circuits from the telephone line, the master GMEC CPE monitors the voltage on the telephone line using its line-in-use circuit 260. The telephone line voltage will rise above a predetermined level if all of the CPEs (i.e., GMEC CPEs and non-GMEC CPEs) connected to the telephone line are in an on-hook condition. If the telephone line voltage rises above this predetermined level, this indicates that the master GMEC CPE has control over all off-hook CPEs coupled to the telephone line. Under these conditions, the master GMEC CPE is allowed to respond to the detected CAS tone as described in more detail below. However, if the telephone line voltage does not rise above the predetermined level, this indicates that the master GMEC CPE does not have control over all off-hook CPEs. That is, there are non-GMEC CPEs coupled to the telephone line which are in an off-hook condition. Under these circumstances, the master GMEC CPE does not respond to the detected CAS tone. Instead, the master GMEC CPE allows the off-hook non-GMEC CPE to respond to the CAS tone, effectively allowing the off-hook non-GMEC CPE to be the master for this limited puφose. If the off-hook non-GMEC CPE transmits the appropriate acknowledge signal in response to the CAS tone, CID information may be received. If the off- hook non-GMEC CPE does not transmit the appropriate acknowledge signal, CID information is not received.

If the master GMEC CPE is to respond to the detected CAS tone, then the second micro-controller 270 within the master GMEC CPE asserts the

TERMINATE_LINE signal to phone line switch 290, thereby maintaining the telephone line 10 in an off-hook condition. The second micro-controller 270 within the master GMEC CPE causes the DTMF generator 280 within the master GMEC CPE to generate the appropriate acknowledge signal, as determined by the priority code of the master GMEC CPE. A DTMF "A" acknowledge signal is

21 generated for an ITM priority code of 6, while a DTMF "D" acknowledge signal is generated for all other ITM priority codes. The generated acknowledge signal is transmitted on the telephone line to the central office or ADSI server.

In response to the acknowledge signal, the central office transmits CID information (or no information), and the ADSI server transmits ADSI information (or no information). For example, an ADSI server will send no information in response to a DTMF "D" signal transmitted by the master GMEC CPE. The central office send no CID information in response to an acknowledge signal if the central office did not actually transmit a CAS signal. The central office or ADSI server will also send no information if the acknowledge signal was not recognized. If the central office transmits CID information, operation proceeds as follows. The CID information transmitted by the central office is detected, decoded, displayed and stored by the Type II full-feature CPEs and the Type III GMEC CPEs (one of which is the master GMEC CPE). After receiving the CID information from the central office, the master GMEC CPE instructs its associated signal generator 202 to transmit an out-of-band CID instruction on the telephone line. This CID instruction includes a data field which includes the CID information received from the central office. The signal detector 201 within each of the satellite GMEC CPEs detects and decodes the CID instruction to obtain the CID information. The first micro-controller 230 within each of the satellite GMEC CPEs stores the CID information, and causes the CID information to be displayed. The CID instruction received by the satellite GMEC CPEs includes a field which indicates the end of the CID instruction. In response to this end field, each of the satellite GMEC CPEs reconnects its associated telephone to the telephone line (by controlling its corresponding relay 215).

Each of the Type II full-feature CPEs and the Type III GMEC CPEs (one of which is the master GMEC CPE) also reconnects its associated telephone to the telephone line upon detecting that the transmission of the CID information is complete. More specifically, the second micro-controller 270 de-asserts the RELAY_OUT signal to de-actuate relay 215 when second micro-controller 270

7 detects that the carrier detect (-CD) signal provided by data reception circuit 240 transitions to a logic high value (indicating the absence of an FSK carrier signal on the telephone line).

If an ADSI server transmits ADSI information, operation proceeds as follows. ADSI data is only transmitted by an ADSI server in response to a DTMF "A" acknowledge signal. As previously described, the arbitration scheme only allows the master GMEC CPE to transmit a DTMF "A" acknowledge signal if the master GMEC CPE is a Type III GMEC CPE which is the only off-hook device on the telephone line. Thus, if an ADSI server is transmitting ADSI data, only the master GMEC CPE is involved in the ADSI session.

If no information is transmitted in response to an acknowledge signal, operation proceeds as follows. After not detecting information for a predetermined period of time after the CAS tone was detected (i.e., 500 msec or another operationally defined interval), each of the GMEC CPES reconnects its associated telephone to the telephone line.

(3) Synchronized Flash

Any GMEC CPE can cause all GMEC CPEs to temporarily disconnect their associated telephones from the telephone line in a synchronized manner by broadcasting an out-of-band BREAK instruction on the telephone line. The

BREAK instruction includes a duration field which defines the amount of time that the telephones will be disconnected from the telephone line. Assuming that the only off-hook CPEs are GMEC CPEs, the break instruction allows a synchronized hook flash operation to be performed when multiple GMEC CPEs are in an off- hook condition. For such a synchronized hook flash operation, the duration field is selected to specify a break duration of approximately 600 msec.

In one embodiment, the BREAK instruction can be generated by pressing a key on the GMEC CPE. This key can be labeled, for example, FLASH. Upon pressing the FLASH key on any GMEC CPE (hereinafter the initiator GMEC CPE), the signal generator 202 within this initiator GMEC CPE generates an out- of-band BREAK instruction. In response to this BREAK instruction, all GMEC CPEs disconnect their associated telephone circuit 205 from the telephone line by asserting the RELAY OUT signal. In response to the pressed FLASH key, the initiator GMEC CPE disconnects its associated telephone circuit from the telephone line by asserting the RELAY OUT signal. Each of the GMEC CPEs then monitors its associated line-in-use circuit 260 to determine when the telephone line exhibits an on-hook condition. Once this on-hook condition is detected, each GMEC CPE begins a counter which counts for the time period specified by the duration field of the BREAK instruction. At the end of this time period, each GMEC CPE re-connects its associated telephone circuit 205 to the telephone line by de-asserting the RELAY OUT signal. If the telephone line does not exhibit an on-hook condition within a predetermined delay period, then each of the GMEC CPEs re-connects its associated telephone circuit 205 to the telephone line by de-asserting the RELAY_OUT signal. The BREAK instruction thereby enables the customer to perform a hook flash operation when more than one GMEC CPE is in an off-hook condition.

The BREAK instruction will be ineffective in performing a hook flash operation if a non-GMEC CPE connected to the telephone line is in an off-hook condition. However, this fact enables the BREAK instruction to be used to determine if a non-GMEC CPE connected to the telephone line is, in fact, currently in an off-hook condition. More specifically, if the telephone line does not exhibit an on-hook condition in response to a BREAK instruction, then an off-hook non- GMEC CPE has been detected on the telephone line.

The BREAK instruction can be used in a similar manner to implement a flash code in an auto-dial operation. In this embodiment, the BREAK instruction is initiated internally, rather than being initiated by pressing a key. The BREAK instruction can also be used to provide a flash pulse to dial a "1" in response to an ADSI request.

Finally, the BREAK instruction can be used to pulse dial a predetermined number, such as 911 , in the presence of one or more off-hook GMEC CPEs. In

11 one such application, one or more of the GMEC CPEs connected to a telephone line includes a dedicated EMERGENCY key. Upon pressing the EMERGENCY key, a predetermined sequence of BREAK instructions are transmitted, thereby causing the GMEC CPEs to engage in a predetermined sequence of hook flash operations, which in turn causes the desired number (e.g., 911) to be pulse dialed.

(4) Remote Call Record Management

The out-of-band signalling capability which exists between GMEC CPEs can also be used to perform various remote call record management functions. Although particular functions are described below, it is understood that other management functions can be implemented using the out-of-band signalling capability to send representative instructions, and that these other functions are considered to be within the scope of the present invention.

Universal new call indicator

In one embodiment, the master GMEC CPE includes the capability of detecting a visual message waiting indicator (VMWI) signal or a stutter dial tone in accordance with conventional techniques. A VMWI signal is an FSK signal which is transmitted by the central office to indicate that the user has received new voice mail messages. The Type III GMEC CPEs and the Type II full-feature GMEC CPEs detect the VMWI signal with their corresponding data reception circuits as previously described. Upon detection of a VMWI signal the master GMEC CPE broadcasts an out-of-band MW ON (message waiting on) instruction on the telephone line. Each of the Type II satellite GMEC CPEs connected to the telephone line, upon receiving the MW_ON instruction, activates a corresponding indicator light to indicate that a voice message is waiting. Advantageously, all GMEC CPEs are thereby simultaneously informed of the new voice message.

The master GMEC CPE is the only GMEC CPE which checks the telephone line for a stutter dial tone (and other call progress tones in the case of a Type III GMEC CPE). This advantageously limits the number of CPEs seizing the

1% telephone line, thereby improving the reliability of the stutter tone detection. To check the telephone line for a stutter dial tone, for example, the master GMEC CPE (Fig. 2) seizes the telephone line by transmitting a TERMINATE_LINE signal to phone line switch 290. This effectively places the telephone line in an off-hook condition. During this time, the data reception circuit of the master GMEC CPE monitors the telephone line, in the manner previously described, to determine whether or not a stutter dial tone exists on the telephone line, using known stutter tone detection means such as those described in U.S. Patent No. 4,953,958, to Morganstein, which utilize the frequency and cadence of the tone as an identifier. If a stutter dial tone is detected, the signal generator of the master GMEC CPE generates the MW_ON instruction. Each of the other GMEC CPEs connected to the telephone line, upon receiving the MW_ON instruction, activates its corresponding indicator light.

When the master GMEC CPE detects a VMWI OFF signal or the absence of a stutter dial tone, the master GMEC CPE broadcasts an out-of-band MW_OFF (message waiting off) instruction. Upon receipt of the MW_OFF instruction, each of the GMEC CPEs connected to the telephone line de-activates its corresponding indicator light. In another embodiment, one or more of the GMEC CPEs includes a MESSAGE OFF key. When the MESSAGE OFF key is pressed, the corresponding GMEC CPE generates the MW_OFF signal, thereby deactivating the indicator lights of the GMEC CPEs connected to the telephone line. The MESSAGE OFF key advantageously allows the customer to manually de-activate the new message indicator lights on the GMEC CPEs.

Remote Call Record Delete

In another embodiment, the GMEC CPEs include a DELETE key. By pressing the DELETE key of a GMEC CPE, the call record which is displayed on this GMEC CPE is deleted on all of the GMEC CPEs. This eliminates the need for the customer to move to each individual CPE to delete a call record.

2η When the user presses the DELETE key on a GMEC CPE (hereinafter the initiator GMEC CPE), the initiator GMEC CPE internally deletes the call record currently displayed by the initiator GMEC CPE. In addition, the initiator GMEC CPE broadcasts an out-of-band DELETE instruction on the telephone line. The DELETE instruction includes a hash field which includes the time stamp and the sequence tag of the call record to be deleted. If the specified call record does not exist, the GMEC CPEs receiving the DELETE instruction do nothing. If the specified call record does exist, the GMEC CPEs receiving the DELETE instruction delete the specified call record and update their respective new call indicators in response to the DELETE instruction.

In a variation of this embodiment, the GMEC CPEs also include a DELETE_ALL key. The customer can press the DELETE_ALL key on an GMEC CPE to delete all of the call records stored in all of the GMEC CPEs. Again, this feature eliminates the need for the user to move to each individual CPE to delete all of the call records from all of the CPEs. When the customer presses the

DELETE_ALL key on an GMEC CPE (hereinafter the initiator GMEC CPE), the initiator GMEC CPE internally deletes all of the call records stored in the initiator GMEC CPE. In addition, the initiator GMEC CPE broadcasts an out-of-band DELETE ALL instruction on the telephone line. Each of the GMEC CPEs receiving the DELETE_ALL instruction delete all of their corresponding call records and update their respective new call indicators in response to the DELETE_ALL instruction.

Remote Call Reviewed Indicator In another embodiment, the GMEC CPEs also include a REVIEWED key.

By pressing the REVIEWED key on an GMEC CPE, the call record which is displayed on this GMEC CPE is marked as having been reviewed on all of the GMEC CPEs. This functionality prevents the customer from confusing reviewed and unreviewed calls. When the customer presses the REVIEWED key on an GMEC CPE (hereinafter the initiator GMEC CPE), the initiator GMEC CPE internally marks as reviewed the call record displayed by the initiator GMEC CPE. In addition, the initiator GMEC CPE broadcasts an out-of-band REVIEWED instruction on the telephone line. The REVIEWED instruction includes a hash field which contains the time stamp and the sequence tag corresponding to the call record to be marked as reviewed. If the specified call record does not exist, the GMEC CPEs receiving the REVIEWED instruction do nothing. If the specified call record does exist, the GMEC CPEs receiving the REVIEWED instruction mark the specified call record as reviewed and update their respective new call indicators in response to the REVIEWED instruction.

In a variation of this embodiment, the GMEC CPEs also include a REVIEWED_ALL key. The customer can press the REVIEWED_ALL key on an GMEC CPE to mark all of the call records stored in all of the GMEC CPEs as reviewed. Again, this feature eliminates the need for the user to move to each individual CPE to mark as reviewed all of the call records from all of the CPEs. When the customer presses the REVIEWED_ALL key on an GMEC CPE (hereinafter the initiator GMEC CPE), the initiator GMEC CPE internally marks as reviewed all of the call records stored in the initiator GMEC CPE. In addition, the initiator GMEC CPE broadcasts an out-of-band REVIEWED_ALL instruction on the telephone line. Each of the GMEC CPEs receiving the REVIEWED_ALL instruction marks as reviewed all of its corresponding call records and updates its respective new call indicators in response to the REVIEWED_ALL instruction.

Private/Public mode

In another embodiment, the GMEC CPEs also include a PRIVATE key which is pressed if the customer would like to make a call using one GMEC CPE, and does not want anyone else to listen to the call using another Type III GMEC CPE or another Type II full-feature GMEC ICPE which is connected to the telephone line. Upon pressing the PRIVATE key on a GMEC CPE (hereinafter the

2>1 initiator GMEC CPE), the initiator GMEC CPE disconnects its associated telephone and transmits an out-of-band TEST instruction to each GMEC CPE attached to the telephone line. Upon receipt of the TEST instruction, any GMEC CPE which can detect the on-hook/off-hook status of its associated telephone (i.e., a Type III GMEC CPE or a Type II full-feature GMEC ICPE) disconnects its associated telephone circuit. The initiator GMEC CPE monitors its line-in-use circuit 260 to determine whether the telephone line is in an on-hook or off-hook condition in response to the TEST instruction. If the initiator GMEC CPE detects that the telephone line is in an off-hook condition via the voltage detected on the telephone line, then a CPE which is incapable of detecting the on-hook/off-hook status of its associated telephone is off-hook. Under these conditions, the customer is informed that he cannot make a private call.

If the initiator GMEC CPE detects that the telephone line is in an on-hook condition, then the initiator GMEC CPE re-connects only its own associated telephone. At this time, the initiator can dial the desired number for the private call. The telephone circuits of the GMEC CPEs which are capable of detecting their corresponding on-hook/off-hook status remain disconnected from the telephone line, such that these GMEC CPEs will not go off-hook if their handsets are lifted. As a result, the master priority arbitration is suspended with the off- hook initiator GMEC CPE having master status during the private session.

The private status is maintained until a PUBLIC instruction is received. A PUBLIC instruction is broadcast by pressing a dedicated PUBLIC key, or when the line-in-use circuit of any GMEC CPE detects an on-hook condition for more than 1.55 seconds (i.e., the initiator GMEC CPE hangs up). After the private status is terminated, the master priority arbitration is reinstated.

(5) Management of Shared Resources

One embodiment of the management of shared resources was previously described in connection with the assignment of priority codes to the ITM signal (i.e., to share the "refuse blocked calls" feature present in one GMEC CPE). In

11 another embodiment, the DTMF dialing capabilities of the master GMEC CPE is shared with a satellite GMEC CPE, which, as previously described, does not include circuitry to allow for ring detection, CAS tone filtering, DTMF generation or line hold/line switch capabilities (See, Fig. 3). To accomplish this, the satellite GMEC CPE includes a dedicated DIAL key. The DIAL key is pressed to dial the number displayed by the satellite GMEC CPE. The satellite GMEC CPE will only respond to a pressed DIAL key if the line-in-use circuit of the satellite GMEC CPE indicates that the telephone line is in an off-hook condition. If this condition exists, the satellite GMEC CPE broadcasts an out-of-band DIAL instruction on the telephone line. The DIAL instruction includes a number field which identifies the telephone number to be dialed. The master GMEC CPE receives the DIAL instruction, and in response, determines whether or not the master GMEC CPE is on-hook. If the master GMEC CPE is on hook, then the master GMEC CPE instructs its DTMF signal generator 280 to generate a series of DTMF signals representative of the telephone number in the number field of the DIAL instruction. In this way the satellite GMEC CPE is able to utilize the functionality of the master to dial the number input on the satellite GMEC CPE, even though the satellite, by itself, is unable to perform this function. The master GMEC CPE does not add the telephone number dialed in response to a DIAL instruction to the redial list of the master GMEC CPE because this telephone number was not dialed by a user of the master GMEC CPE.

Another embodiment of a shared resource is a message server system which enables Type II satellite GMEC CPEs to access call records from a server GMEC CPE. To implement this message server system, one of the GMEC CPEs is automatically selected to be the server GMEC CPE using a server arbitration scheme. The server GMEC CPE can be a Type III GMEC CPE, a Type II GMEC ICPE or a Type II GMEC adjunct. The server GMEC CPE operates concurrently with the master GMEC CPE, as previously described, to coordinate in the management of shared resources as herein described. In the server arbitration scheme, each GMEC CPE which is capable of being the server GMEC CPE generates an out-of-band ITS (I'm The Server) instruction which includes a field which indicates the number of call records stored in the GMEC CPE generating the ITS instruction. The GMEC CPE having the greatest number of stored call records is designated as the server GMEC CPE. (The remaining GMEC CPEs stop generating their respective ITS instructions upon detecting another GMEC CPE having a greater number of stored call records). The number of call records stored by the server GMEC CPE changes dynamically during normal operation of the message server system. That is, new call records can be stored or old call records can be deleted. The current number of call records stored in the server GMEC CPE is communicated to the other GMEC CPEs by the ITS instruction. If a non-server GMEC CPE detects that it is storing more call records than the current server GMEC CPE, then this non-server GMEC CPE generates an ITS instruction which indicates this greater number of call records. Upon receiving this ITS signal, the current server GMEC CPE relinquishes its server status by ceasing to generate the ITS signal. As a result, the non-server GMEC CPE having the greater number of call records becomes the new server GMEC CPE.

A Type II satellite GMEC CPE can access the call records stored in the server GMEC CPE using an out-of-band REQUEST signal. The REQUEST signal, which is generated when the user presses a designated key on the Type II satellite GMEC CPE, includes an index field which identifies the number of the call record to be retrieved from the server GMEC CPE. This index field is initially set to a '0' value, thereby allowing the Type II satellite GMEC CPE to retrieve a predetermined call record stored by the server GMEC CPE (typically the last call record received). For example, in one possible scheme for record retrieval, the user, by sequentially pressing the designated key (or keys) on the Type II satellite GMEC CPE, increments (or decrements) the index field, thereby allowing sequential call records to be accessed by the Type II satellite GMEC CPE. Upon receiving the REQUEST instruction, the server GMEC CPE transmits either an out-of-band RECORD instruction or an out-of-band NO RECORD instruction. The server transmits the RECORD instruction if the

3»τ call record identified by the REQUEST instruction exists within the memory of the server GMEC CPE. The RECORD instruction includes an index field which identifies the location of the call record within the memory of the server GMEC CPE (i.e., Record 0, Record 1, ... Record N). The RECORD instruction also includes a data field which provides the call record information. The RECORD instruction further includes a hash field which includes the time stamp and the sequence tag of the call record. The hash field is provided so that the Type II satellite GMEC CPE is capable of identifying the call record universally within all of the GMEC CPEs connected to the telephone line. (The index field only identifies the call record within the memory of the server GMEC CPE). By providing the Type II satellite GMEC CPE with the hash field, the Type II satellite GMEC CPE is capable of issuing a DELETE or REVIEW instruction to delete or mark as reviewed the call record in all GMEC CPEs.

The server transmits the NO RECORD instruction if the call record identified by the REQUEST instruction does exist within the server GMEC CPE. Upon receiving the NO_RECORD instruction, the Type II satellite GMEC CPE displays an appropriate message, such as "End of List". The NO_RECORD instruction also includes an index field to identify the accessed location within the memory of the server GMEC CPE. The message server system advantageously eliminates the need for call record memory within Type II satellite GMEC CPEs. The message server system also advantageously increases the call record capacity of the system to correspond with the call record capacity of the GMEC CPE having the largest memory capacity. To summarize, the GMEC protocol provides the following classifications of service: inter-CPE control, inter-CPE communication, and inter-CPE coordination. Inter-CPE control refers to the point to multi-point control which is accomplished by the following instructions: ITM, IMOFF, RING, MW ON, MW_OFF, PUBLIC, PRIVATE and ITS. Inter-CPE communication refers to the communication of information accomplished by the following instructions:

3S^" REQUEST, RECORD, NO_RECORD, ERROR, CID, DELETE, DELETE_ALL, REVIEW and REVIEW ALL. Inter-CPE co-ordination refers to the telephone line co-ordination which is accomplished by the following instructions: BREAK, DIAL, TEST and CAS. In another embodiment, the present invention can be expanded to include

Type I GMEC CPEs. Type I GMEC CPEs include all of the functionalities of a conventional Type I CPE, plus selected functionalities enabled by the GMEC protocol. In general, there are three different kinds of Type I GMEC CPEs: a Type I GMEC integrated CPE (ICPE), a Type I GMEC adjunct, and a Type I satellite GMEC CPE. Table 5 summarizes selected capabilities of these Type I GMEC CPEs.

Table 5

Type I Type 1 Type I

GMEC ICPE GMEC Adjunct Sat. GMEC CPE

Can break line NO NO NO

Receives CAS NO NO NO

Receives FSK YES YES NO

Can be Master YES YES NO

Detects LIU YES NO NO

Detects own LIU YES NO NO

Type I GMEC CPEs which are capable of being the master GMEC CPE (i.e., Type I GMEC ICPEs and Type I GMEC Adjuncts) are given an ITM priority code of -1 for both on-hook and off-hook conditions. Type I GMEC ICPEs and Type I GMEC adjuncts are substantially similar to the Type II GMEC CPE 2 illustrated in Fig. 2. However, Type I GMEC ICPEs do not include relay 215, CAS filters 275, or second microcontroller 270. Type I GMEC adjuncts do not include relay 215, CAS filters 275, second microcontroller 270, DTMF generator 280, line hold circuit 285, line switch 290, or line in use circuit 260. Type I satellite GMEC CPEs are substantially identical to the Type II satellite GMEC

CPE 3 illustrated in Fig. 3. However, Type I satellite GMEC CPEs do not include

2A. relay 215 or line in use circuit 260 as illustrated in Fig. 3. Type I GMEC CPEs operate in accordance with the GMEC protocol as previously described. Note that Type I GMEC CPEs cannot participate in GMEC operations which require breaking the line (i.e., synchronized flash). The foregoing has described the principles and preferred embodiments of the present invention. However, the invention should not be construed as being limited to the particular embodiments described. For example, different devices can be used from the micro-controllers, detection circuits and tone generators described herein. Also, different devices may be used to present the CID information to the user(s), including computers, audio systems or other signaling devices. Further, some functions can be combined in a custom digital processing chip. In addition, different implementations of the LIU, line hold, and phone line switch are possible. Thus, above-described embodiments should be regarded as illustrative rather than restrictive. Variations can be made to those embodiments by workers skilled in the art without departing from the scope of the present invention as defined by the following claims.

11

Claims

CLAIMSWhat is Claimed is:

1. A customer premises equipment (CPE) for connection to a telephone line, the CPE comprising: a controller circuit; a signal generator coupled to the controller circuit and adapted for connection to the telephone line, wherein the controller circuit causes the signal generator to generate a plurality of instructions for transmission on the telephone line; and a signal detector coupled to the controller circuit and adapted for connection to the telephone line, wherein the signal detector receives a plurality of instructions transmitted on the telephone line and provides these instructions to the controller circuit, wherein the controller circuit controls the operation of the CPE in response to instructions received from the signal detector.

2. The CPE of Claim 1 , further comprising a key coupled to the controller circuit, wherein the controller circuit causes the signal generator to transmit a predetermined instruction when the key is pressed.

3. The CPE of Claim 2, wherein the predetermined instruction causes a dial function to be performed by another CPE coupled to the telephone line.

4. The CPE of Claim 2, wherein the predetermined instruction causes a hook flash operation to be performed by another CPE coupled to the telephone line.

5. The CPE of Claim 2, wherein the predetermined instruction causes a call record to be deleted by another CPE coupled to the telephone line.

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6. The CPE of Claim 2, wherein the predetermined instruction causes another CPE coupled to the telephone line to delete all of its associated call records.

7. The CPE of Claim 2. wherein the predetermined instruction causes a call record to be marked as reviewed by another CPE coupled to the telephone line.

8. The CPE of Claim 2, wherein the predetermined instruction causes another CPE coupled to the telephone line to mark as reviewed all of its associated call records.

9. The CPE of Claim 2, wherein the predetermined instruction causes another CPE coupled to the telephone line to disconnect its associated telephone from the telephone line.

10. The CPE of Claim 2, wherein the predetermined instruction causes another CPE coupled to the telephone line to turn off its associated message waiting indicator.

11. The CPE of Claim 1 , further comprising an acknowledge signal generator coupled to the controller circuit and adapted for connection to the telephone line, wherein the controller circuit enables and disables the acknowledge signal generator in response to instructions received from the signal detector.

12. The CPE of Claim 1, wherein the controller circuit determines a priority code of the CPE.

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13. The CPE of Claim 12, wherein the priority code of the CPE is dependent upon the on-hook/off-hook status of the CPE.

14. The CPE of Claim 13, wherein the priority code of the CPE is higher when the CPE is in an off-hook condition than when the CPE is in an on- hook condition.

15. The CPE of Claim 12, wherein the controller circuit causes the signal generator to transmit an instruction containing the priority code of the CPE.

16. The CPE of Claim 12, wherein the instructions received by the signal detector include a priority code associated with a master CPE, and further wherein the controller circuit causes the signal generator to transmit an instruction which includes the priority code of the CPE when the priority code of the CPE exceeds the priority code associated with the master CPE.

17. The CPE of Claim 1, further comprising an alerting signal detector circuit coupled to the controller circuit and adapted for connection to the telephone line, wherein the alerting signal detector circuit detects the presence of an alerting signal on the telephone line, and in response, causes the signal generator to generate an acknowledge signal detected instruction.

18. The CPE of Claim 1 , wherein the controller circuit causes the signal generator to generate an instruction which contains caller identification information received by the CPE.

19. The CPE of Claim 1, wherein the controller circuit causes the signal generator to generate an instruction which causes another CPE connected to the telephone line to disconnect its associated telephone from the telephone line.

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20. The CPE of Claim 1 , further comprising a ring detector circuit coupled to the controller circuit and adapted for connection to the telephone line, wherein the ring detector circuit informs the controller circuit of the presence of a ring signal on the telephone line, and further wherein the controller circuit causes the signal generator to generate an instruction which informs another CPE connected to the telephone line of the presence of a ring signal.

21. The CPE of Claim 1 , wherein the controller circuit monitors the telephone line to detect the presence of a message waiting signal, wherein the controller circuit causes the signal generator to generate an instruction which informs another CPE connected to the telephone line of the presence of a message waiting signal.

22. The CPE of Claim 1, wherein the signal generator generates an instruction which causes another CPE coupled to the telephone line to connect its associated telephone to the telephone line.

23. The CPE of Claim 1, wherein the signal generator generates instructions at frequencies which exists outside of the range of frequencies used for voice and modem communications on a telephone line.

24. The CPE of Claim 1 , wherein the signal detector receives instructions at frequencies which exists outside of the range of frequencies used for voice and modem communications on a telephone line.

25. A customer premises equipment (CPE) for connection to a telephone line, the CPE comprising: signal generator means for broadcasting a plurality of instructions on the telephone line;

<*i signal detector means for receiving a plurality of instructions broadcast on the telephone line; a controller coupled to the signal detector and the signal generator for controlling the operation of the CPE in response to instructions received by the signal detector means, and for controlling the operation of other

CPEs connected to the telephone line by controlling the instructions broadcast by the signal generator means.

26. A telephone system comprising: a telephone line; a first customer premises equipment (CPE) comprising a first signal generator for generating a plurality of instructions, a first signal detector for receiving a plurality of instructions, a first controller coupled to the first signal generator and the first signal detector, a first telephone circuit, and a first relay connected between the first telephone circuit and the telephone line, the first relay being controlled by the first controller; and a second CPE comprising a second signal generator for generating a plurality of instructions, a second signal detector for receiving a plurality of instructions, a second controller coupled to the second signal generator and the second signal detector, a second telephone circuit, and a second relay connected between the second telephone circuit and the telephone line, the second relay being controlled by the second controller.

27. The telephone system of Claim 26, wherein the first CPE is a Type III CPE.

28. The telephone system of Claim 27, wherein the second CPE is a Type II CPE.

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29. The telephone system of Claim 27, wherein the second CPE is a Type III CPE.

30. The telephone system of Claim 26, wherein the first and second CPEs are both Type II CPEs.

31. The telephone system of Claim 26, wherein the first CPE and the second CPE is each identified by type as either a Type II CPE or a Type III CPE, wherein the first controller assigns the first CPE a first priority code based on the type of the first CPE, and the second controller assigns the second CPE a second priority code based on the type of the second CPE.

32. The telephone system of Claim 31 , wherein the first priority code is further based on the on-hook/off-hook status of the first telephone circuit, and the second priority code is further based on the on-hook/off-hook status of the second telephone circuit.

33. A method of operating a telephone system comprising the steps of: connecting a first customer premises equipment (CPE) and a second CPE to a telephone line; assigning a first priority code to the first CPE, wherein the first priority code is determined by the capabilities of the first CPE; assigning a second priority code to the second CPE, wherein the second priority code is determined by the capabilities of the second CPE; periodically transmitting a first instruction with the first CPE, wherein the first instruction includes the first priority code; receiving the first instruction with the second CPE; comparing the first priority code with the second priority code within the second CPE; and

Hi periodically transmitting a second instruction with the second CPE when the second priority code exceeds the first priority code, wherein the second instruction includes the second priority code; receiving the second instruction with the first CPE; comparing the second priority code with the first priority code within the first CPE; and ceasing to transmit the first instruction with the first CPE when the first CPE determines that the second priority code contained within the second instruction exceeds the first priority code.

34. The method of Claim 33, further comprising the step of increasing the first priority code when the first CPE transitions from an on-hook condition to an off-hook condition.

35. The method of Claim 34, further comprising the step of increasing the second priority code when the second CPE transitions from an on-hook condition to an off-hook condition.

36. The method of Claim 33, wherein the first CPE is a Type III CPE and the second CPE is a Type II CPE, and the first priority code is greater than the second priority code.

37. The method of Claim 33, further comprising the steps of: responding to an alerting signal on the telephone line with the first CPE if the first CPE is periodically transmitting the first instruction; and responding to an alerting signal on the telephone line with the second CPE if the second CPE is periodically transmitting the second instruction.

38. A method of operating a telephone system comprising the steps of: connecting a first customer premises equipment (CPE) to a telephone line and a second CPE to a telephone line; monitoring the telephone line with the first CPE to determine whether an alerting signal is present on the telephone line; 5 generating an acknowledge signal with only the first CPE when the first CPE determines an alerting signal is present on the telephone line; receiving information transmitted on the telephone line in response to the acknowledge signal with the first CPE; broadcasting an instruction on the telephone line with the first CPE, o wherein the instruction is representative of the information received by the first CPE; and receiving the instruction broadcast on the telephone line with the second CPE, whereby the second CPE receives the information received by the first CPE. 5

39. A method of operating a telephone system comprising the steps of: connecting a plurality of customer premises equipments (CPEs) to a telephone line; selecting one of the plurality of CPEs to be a master CPE; 0 monitoring the telephone line with the master CPE to determine when an alerting signal is present on the telephone line; generating an acknowledge signal with only the master CPE when the master CPE determines an alerting signal is present on the telephone line; 5 receiving information transmitted on the telephone line in response to the acknowledge signal with the master CPE; broadcasting an instruction on the telephone line with the master CPE, wherein the instruction is representative of the information received by the master CPE; and

i receiving the instruction broadcast on the telephone line with the CPEs which are not the master CPE, whereby the CPEs which are not the master CPE receive information received by the master CPE.

40. A method of operating a telephone system comprising the steps of: connecting a plurality of customer premises equipments (CPEs) to a single telephone line; and coordinating the operation of the plurality of CPEs by transmitting a plurality of instructions between the plurality of CPEs using an out-of-band signalling protocol.