Sip Register Server; Pulse Code Modulation - ZyXEL Communications VMG5313-BXB SERIES User Manual

In the following example, you want to use client device A to call someone who is using client device
C.
Client device A sends a call invitation for C to the SIP redirect server (B).
1
The SIP redirect server sends the invitation back to A with C's IP address (or domain name).
2
Client device A then sends the call invitation to client device C.
3
Figure 140 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.

Pulse Code Modulation

Pulse Code Modulation (PCM) measures analog signal amplitudes at regular time intervals and
converts them into bits.
Chapter 22 Voice
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