An ip based telephone system

"METHODS TO ESTABLISH A PHONE CALL BETWEEN A SUBSCRIBER AND AN ADDITIONAL PART, AND TO ESTABLISH A CALL FROM A CALLING PART TO A CALLED PARTY, TELECOMMUNICATION SYSTEM INCLUDING AT LEAST ONE VOICE TRAINING, ONE VOICE AND ONE LAND TRAINER. BETWEEN A VOICE TRAFFIC SUBSCRIBER AND A TELEPHONE CENTER, TELECOMMUNICATIONS SYSTEM TO SUPPORT TELEPHONE TRAFFIC TO AND AT LEAST ONE SUBSCRIBER, AND, TELEPHONE CENTER ". The invention provides a hybrid arrangement, which allows an existing circuit-switched telephone network to be deployed into a packet-switched network. The underlying circuit-switched transport network is replaced with that of an IP-based packet-switched network (30), while circuit-switched infrastructure such as terminals, telephone exchanges and the like are maintained. In preferred embodiments of the invention, both a subscriber (10, 11, 20, 21) and a local telephone exchange (40, 50) are connected, and separated, by an IP-based packet-switched network such as the Internet (30) . Signaling between the subscriber (10, 11, 20, 21) and the telephone exchange (40, 50) is carried out using a standard user-to-network protocol, such as V5.1 for PSTN and ISDN BRI or DSS 1 for ISDN PRI . This standard user-to-network protocol is superimposed on an IP-based network protocol, such as TCP or UDP over IP.