H.323 and SIP

1. H.323 and SIP j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

2. Multipoint Control Unit Gatekeeper Packet Based Networks Terminal Terminal Gateway H.323 – VoIP components optional optional Circuit Switched Networks optional j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

3. H.323 - Terminals • H.323 terminals are client endpoints. • IP telephones or IP soft phones that must support: • Data Control (H.225 and H245). • RTP (Real-Time Transport Protocol)/RTCP (Real Time Control Protocol) for media packets. • Audio codecs. • Video codecs support is optional. j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

4. H.323 - Multipoint Control Unit • Also called conference server • Setup Call for three or more endpoints j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

5. H.323 – Gatekeepers • Gatekeepers provide these functions: • Admission control • Bandwidth control • Zone management • Call control signaling • Call authorisation • Bandwidth management • Call management • Built in at Cisco 2500, 2600, 3600, 3700, 7200 routers j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

6. H.323 – Gateway • A gateway is a router or a computer installed with NIC & modem. • It provides translation between H.323 and non-H.323 endpoints. j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

7. SIP j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

8. Redirect Server Registrar Server Packet Based Networks SIP - VoIP Components PSTN User Agent Gateway Proxy Server j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

9. User Agent • User agent are client endpoints. • Can be IP telephones or IP soft phones. j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

10. Proxy Server • An intermediary program that acts as both a server and a client to make requests on behalf of other clients. • Requests are serviced internally or by passing them on, possibly after translation, to other servers. • Interprets, rewrites or translates a request message before forwarding it. j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

11. Redirect Server • A server that accepts a SIP request, maps the address into zero or more new addresses and returns these addresses to the client. • Unlike a proxy server, the redirect server does not initiate its own SIP request. • Unlike a user agent server, the redirect server does not accept or terminate calls. j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

12. Registrar Server • A server that accepts REGISTER requests. • The register server may support authentication. • A registrar server is typically co-located with a proxy or redirect server and may offer location services. j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

13. SIP addressing • The SIP address is identified by a SIP URI, in the format: user@host. • Examples of SIP URIs: • sip:hostname@vovida.org • sip:m28@192.168.0.5 • sip:294284@www.staffs.ac.uk j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

14. Packet Based Networks SIP – Implementation SIP Server: Proxy Server + Registrar Server + Redirect Server 1 Registration + call setup Call setup 2 User Agent User Agent 3 Invitation j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

15. Comparing H.323 and SIP components j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

16. Useful SIP server and IP soft phone • SIP Server: • OnDo SIP server • Router with build-in VoIP features • IP soft phones: • Windows Messenger 5.0 or higher • SJPhone j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk

17. j.c.westlake@staffs.ac.uk & k.k.chai@staffs.ac.uk