Operation Manual – Process Server Configuration
H3C XE 200/2000 IP PBX
Chapter 4 SIP Overview
4-5
1)
Phone 1 dials the number of Phone 2.
2)
Upon receipt of the call, VG 1 sends a session request (INVITE) to SIP Server.
3) SIP Server consults its database for information corresponding to the number of
Phone 2. If such information is available, it forwards the request to VG 2.
4)
VG 2, after receiving the request, responds to SIP Server and has Phone 2 ring if
Phone 2 is available.
5) SIP Server forwards a response to VG 1. The response discussed here includes
two messages: provisional (180 Ringing) and success (200 OK). When informing
Phone 2 about invitation, VG 2 returns a 180 Ringing message to SIP Server;
when Phone 2 is picked up, VG 2 returns a 200 OK message to SIP Server
indicating the call is connected.
6) VG 1 sends an acknowledgement to VG 2, indicating it is ready for the
conversation.
This completes the INVITE –– Final response (200) –– ACK three-way handshake. See
Figure 4-3
for the message interactions throughout the call setup process.
INVITE w ith SDP1
100 TRYING
INVITE w ith SDP1
100 TRYING
180 Ringing
180 Ringing
200 OK w ith SDP2
200 OK w ith SDP2
ACK for 200
ACK for 200
RTP/RTCP
BYE
BYE
200 for BYE
200 for BYE
Caller
PROXY
Callee
Figure 4-3
Call setup procedures through a proxy server
This is a simple scenario where only one proxy server is involved and no registrar is
present. A complex scenario, however, may involve multiple proxy servers and
registrars.
III. Call redirect
When a SIP redirect server receives a session request, it sends back a response
indicating address of the called SIP endpoint instead of forwarding the request. The
Summary of Contents for XE 200/2000 IP
Page 7: ...Basic Configuration ...
Page 42: ...Process Server Configuration ...
Page 82: ...Location Server Configuration ...
Page 182: ...Feature ...
Page 259: ...System Management ...
Page 341: ...IP Performance and Application ...
Page 349: ...Media Server ...
Page 360: ...Call Services ...
Page 507: ...Appendix A ...
Page 511: ...Appendix B ...