Chapter 22 Voice
EMG6726/8726-B10A User’s Guide
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SIP Redirect Server
A SIP redirect server accepts SIP requests, translates the destination address to an IP address and sends
the translated IP address back to the device that sent the request. Then the client device that originally
sent the request can send requests 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
.
1
Client device
A
sends a call invitation for
C
to the SIP redirect server (
B
).
2
The SIP redirect server sends the invitation back to
A
with
C
’s IP address (or domain name).
3
Client device
A
then sends the call invitation to client device
C
.
Figure 150
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.
