Presentation of VoIP protocols and Codecs Supported by IP PBX

Mihai Constantin
“Luxoft România”, 167 Calea Floreasca, Bucharest, Romania, PhD student at “Politehnica University of Bucharest

Abstract: This article explains Voice over IP and differences between VoIP networks and switched circuits of traditional voice networks. We will make a short introduction to the need for VoIP, with the history and future potential of each. We analyse also security considerations and capabilities of these protocols to work under certain topologies such as Network Address Translation (NAT). Main VoIP protocols supported by IP PBX to be discussed are: H323, SIP. Codecs are the means by which analog voice may be converted to a digital signal and transmitted over the Internet. We also explore the main codecs used, and differences between them in terms of bandwidth requirements (compression level) and quality: G.711, G.729, and MP3.

Keywords: VoIP, NAT, SIP, H323, G.711, G.720, Codec, MP3.

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Mihai Constantin, Presentation of VoIP protocols and Codecs Supported by IP PBX, Romanian Journal of Information Technology and Automatic Control, ISSN 1220-1758, vol. 20(3), pp. 33-36, 2010.