271
Figure 658 Message exchange for a UA to register with a Registrar
Call setup
SIP operates in the Client/Server mode and sets up calls through communication between UA and
proxy server.
Figure 659 Network diagram
In the previous figure, Telephone A wants to call Telephone B, and Router A and Router B work as
SIP endpoints (UAs).
The following is the procedure for connecting a call from Telephone A to Telephone B:
1. Telephone A sends the number of Telephone B.
2. Upon receipt of the call, Router A sends a session request (INVITE) to the proxy server.
3. The proxy server consults its database for information corresponding to the number of
Telephone B. If such information is available, it forwards the request to Router B.
4. Router B, after receiving the request, responds to the proxy server and makes Telephone B ring
if Telephone B is available.
5. The proxy server forwards the response to Router A. The response discussed here includes
two provisional response messages (100 Trying and 180 Ringing) and one success response
(200 OK).
Figure 660 sh
ows the com
plete call setup procedure.
To Next Page
Loading...
Need help?
General
