TIPHON (Telecommunications and Internet Protocol Harmonization Over Networks) is an ETSI working group that aims to ensure that users of packet-switched IP networks can communicate with others from circuit-switched networks such as the telephone network, ISDN or the GSM network. TIPHON dealt, among other things, with VoIP
and then with telecommunication services over the IP protocol. Thesolutions proposed by the TIPHON working group feed into the Next Generation Networks
(NGN). TIPHON, together with SPAN (Services and Protocols for Advanced Networks), forms the TISPANworking group.