ZyXEL Communications VMG8825-B Series User Manual page 249

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