A protocol enhancer (PE) is interfaced between a home location register (HLR) associated with a home mobile telecommunications network and a serving mobile switching center/visitor location register (MSC/VLR) associated within a visited mobile telecommunications network. Whenever a mobile station associated...http://www.google.ca/patents/US5943619?utm_source=gb-gplus-sharePatent US5943619 - Shared interworking of subscriber features within mobile telecommunications networks
