Chapter 9 Voice

to the IP address that it received back from the redirect server. Redirect servers do not initiate SIP requests.

In the following example, you want to use client device A to call someone who is using client device C.

1Client device A sends a call invitation for C to the SIP redirect server (B).

2The SIP redirect server sends the invitation back to A with C’s IP address (or domain name).

3Client device A then sends the call invitation to client device C.

Figure 98 SIP Redirect Server

SIP Register Server

A SIP register server maintains a database of SIP identity-to-IP address (or domain name) mapping. The register server checks your user name and password when you register.

RTP

When you make a VoIP call using SIP, the RTP (Real time Transport Protocol) is used to handle voice data transfer. See RFC 1889 for details on RTP.

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P-2812HNU-51c User’s Guide