Voice over IP (VoIP) allows voice traffic to be carried over an IP data network at lower bandwidth than traditional telephone networks. It provides benefits such as lower communication costs, convergence of voice and data infrastructure, and new multimedia applications. However, VoIP also faces issues including delay, congestion, jitter, packet loss, bandwidth limitations, echo, interoperability between different systems, and ensuring scalability. The two main VoIP protocols are the Session Initiation Protocol (SIP) and H.323. VoIP adoption is growing due to the increasing use of IP networks, and it provides opportunities for lower telephone costs and innovative services. However, challenges remain regarding quality of service, interoperability, and developing carrier-grade

1. Voice over IP: Issues and Protocols Dhigha D Sekaran Sunil Chintakindi

2. Voice over IP: An Introduction Voice over IP is a technology allowing an enterprise to carry voice traffic over an IP data network at substantially reduced bandwidth. It is a a set of facilities for managing the delivery of multimedia information (including fax transmission) in digital form in discrete packets

5. A Simple VoIP Network… IP Network PBX PC Phone VoIP Gateway Server VoIP Gateway Frame Relay or ATM Link LAN Fax

18. SIP in redirect mode…..

19. SIP in proxy mode….

21. H.323 …contd Terminals: Terminals Provide Real-time communications. They must support voice/video/data communications. The most common H.323 Terminal today is Microsoft net meeting Gateway: H.323 gateways provide services to H.323 clients so that they can communicate with non H.323 clients. The gateway must provide translations between different transmission formats, communication procedures, and audio codecs Gatekeepers: They provide call control services for H.323 endpoints, such as address translation and bandwidth management. If they are present in the network the endpoint must use their services. The H.323 standards define mandatory as well as optional services for the gatekeeper. Multiple Control Units(MCUs): They provide conferences of 3 or more endpoints

22. Comparison of SIP and H.323 SIP H.323 IETF MMMUSIC ITU_T Proxy Gatekeeper Large and small conference MCU based control unit Firewall friendly complex, multiple protocols Multicast signaling ----- Personnel mobility Not(yet) SSL, HTTP security work in progress Post dial delay:1.5RTT 8.5RTT Text based binary based. 60+ pages 200 complex pages!!! Easy implementation , Debugging very complex Can be implemented using Java, Tcl,Perl mostly only in C/C++

23. Supporting VoIP Protocols SDP(Session Description Protocol) Intended for describing multimedia sessions RSVP(Resource Reservation Protocol) for prioritization of voice packets RTP(Real time Protocol) for sequencing of packets H.225 : Specifies messages for call control including signaling, registration and admission H.245 -Specifies messages for opening and closing channels H.261 -Video codec for audiovisual services at 64kbps H.263 - New Video codec for video over POTS

32. Growth of the Internet

34. Internet Telephony market

35. Internet Telephony Market Growth

39. Questions and Answers…..