Accessing telephony services from the Internet

Networks exist to provide services to users. Increasingly, the networks on which the services reside are not the same as the networks from which the services are accessed. This leads to the problem on how to best provide such services transparently when the access protocols differ. We discusses a methodology to make available the existing services residing in a network whose protocols are distinct from the network where the access attempt is made. We propose a technique we term call model mapping with state sharing and demonstrate it in the telecommunication domain where we access traditional telephony services residing on the telephone network from Internet telephony endpoints residing on the Internet. KeywordsSIP; H.323; services; PSTN; call models; SS7; state machines