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Chapter 23 Voice
VMG8825-B Series User’s Guide
249
Figure 151
SIP Call Through Proxy Servers
The following table shows the SIP call progression.
1
User Agent 1
sends a SIP INVITE request to
Proxy 1
. This message is an invitation to
User Agent 2
to
participate in a SIP telephone call.
Proxy 1
sends a response indicating that it is trying to complete the
request.
2
Proxy 1
sends a SIP INVITE request to
Proxy 2
.
Proxy 2
sends a response indicating that it is trying to
complete the request.
3
Proxy 2
sends a SIP INVITE request to
User Agent 2
.
Table 113 SIP Call Progression
UA 1
PROXY 1
PROXY 2
UA 2
Invite
Invite
100 Trying
Invite
100 Trying
180 Ringing
180 Ringing
180 Ringing
200 OK
200 OK
200 OK
ACK
RTP
RTP
BYE
200 OK
DSL
DSL