ZyXEL Communications P8802T User Manual page 227

The following figure shows the SIP and session traffic flow between the user
agents (UA 1 and UA 2) and the proxy servers (this example shows two proxy
servers, PROXY 1 and PROXY 2).
Figure 98 SIP Call Through Proxy Servers
UA 1
The following table shows the SIP call progression.
Table 81 SIP Call Progression
UA 1
Invite
ACK
RTP
200 OK
User Agent 1 sends a SIP INVITE request to Proxy 1. This message is an
1
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.
Basic Home Station VDSL2 P8802T User's Guide
PROXY 1
SIP
PROXY 1
Invite
100 Trying
180
Ringing
200 OK
PROXY 2
SIP
SIP & RTP
PROXY 2
Invite
100 Trying
180
Ringing
200 OK
Chapter 15 Voice
SIP
UA 2
UA 2
180
Ringing
200 OK
RTP
BYE
227