Zyxel IES-1000 EE [106/368] Sip call progression

Zyxel IES-1000 EE [106/368] Sip call progression
Chapter 17 VoIP
VOP1224-61 User’s Guide
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2 The SIP proxy server forwards the call invitation to C.
Figure 41 SIP Proxy Server
17.1.3.3 SIP Registrar Server
A SIP registrar server (also known as a register server) maintains a database of
SIP identity-to-IP address (or domain name) mapping. The registrar server checks
your user name and password when you register.
17.1.4 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.
17.1.5 SIP Call Progression
Usually, the SIP UAC sets up a phone call by sending a request to the SIP proxy
server. Then, the proxy server looks up the destination to which the call should be
forwarded (according to the URI requested by the SIP UAC). The request may be
forwarded to more than one proxy server before arriving at its destination.
The response to the request goes to all the proxy servers through which the
request passed, in reverse sequence. Once the session is set up, session traffic is
sent between the UAs directly, bypassing all the proxy servers in between.
A
B
C
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