Sip Service Domain; Sip Call Progression; Sip Client Server; Table 31 Sip Call Progression - ZyXEL Communications MAX-200M1 Series User Manual

ZyXEL MAX-200M1 Series User's Guide

10.1.3.2 SIP Service Domain

The SIP service domain of the VoIP service provider (the company that lets you make phone
calls over the Internet) is the domain name in a SIP URI. For example, if the SIP address is
1122334455@VoIP-provider.com, then "VoIP-provider.com" is the SIP service domain.

10.1.4 SIP Call Progression

The following figure displays the basic steps in the setup and tear down of a SIP call. A calls
B.

Table 31 SIP Call Progression

A
1. INVITE
4. ACK
6. BYE
1 A sends a SIP INVITE request to B. This message is an invitation for B to participate in a
SIP telephone call.
2 B sends a response indicating that the telephone is ringing.
3 B sends an OK response after the call is answered.
4 A then sends an ACK message to acknowledge that B has answered the call.
5 Now A and B exchange voice media (talk).
6 After talking, A hangs up and sends a BYE request.
7 B replies with an OK response confirming receipt of the BYE request and the call is
terminated.

10.1.5 SIP Client Server

SIP is a client-server protocol. A SIP client is an application program or device that sends SIP
requests. A SIP server responds to the SIP requests.
When you use SIP to make a VoIP call, it originates at a client and terminates at a server. A
SIP client could be a computer or a SIP phone. One device can act as both a SIP client and a
SIP server.
106
5.Dialogue (voice traffic)
B
2. Ringing
3. OK
7. OK
Chapter 10 SIP