Voice on IP: Internet, fixed and mobile

Voice over IP (VoIP) is a technology for transporting digitized voice over an IP network, and for establishing communications between IP telephones or softphones. The use of an analog telephone connected to a VoIP converter box or Internet telephony gateway is also covered.

The first part of this dossier provides a state-of-the-art overview of the architectures in place to access, on the one hand, fixed telephony over circuit (from home or the company), low-speed Internet (from home with a 56K modem) and high-speed Internet (from home with an ADSL modem or the company intranet), and on the other hand, mobile telephony and mobile Internet via the mobile network (GSM/GPRS/EDGE and UMTS/HSPA). We'll also look at the challenges involved in migrating to VoIP, particularly in terms of interoperability, quality of service, security and continuity of service linked to mobility. In order to open up new perspectives for VoIP, we will place it in the context of new convergent architectures, with fixed-mobile convergence (FMC) and I-WLAN, UMA/GAN and VCC architectures, on the one hand, and the replacement of circuit-switched transport networks by "all-IP" in the context of TISPAN Release 1 and LTE/SAE architectures, on the other.

The second part [TE 7 533] describes the main standards for call control (H.323, SIP, MGCP and Megaco/H.248), quality of service (DiffServ, RSVP, VAD, UEP/UED and MOS), source coding (codecs), transmission of digitized voice frames (RTP/RTCP, UDP/UDP-Lite, IP), compression (ROHC, SigComp) and security (HTTP Digest, IPsec, TLS, SRTP).

The third part [TE 7 534] covers the implementation of VoIP in the context of, firstly, Internet telephony, with examples of VoIP converter boxes, residential gateways (or "boxes") and softphones; secondly, IP telephony, with examples of IP telephones, IP PBXs, VoIP platforms and Internet telephony gateways; and thirdly, mobile VoIP. The examples of equipment and architectures are taken from public technical specifications for current industrial products, and are offered for illustrative purposes, without being exhaustive.