ZyXEL Communications P-2608HWL-Dx Series - Manual (Page 152)

P-2608HWL-Dx Series User’s Guide
152 Chapter 11 SIP
11.1.3.2 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
[email protected] , then “VoIP-provider.com” is the SIP service domain.
11.1.4 SIP Call Progression
The following figure displays the basic steps in the setup and tear down of a SIP call. A calls
B.
A sends a SIP INVITE request to B. This message is an invitation for B to participate in a SIP
telephone call.
6 B sends a response indicating that the telephone is ringing.
7 B sends an OK response after the call is answered.
8 A then sends an ACK message to acknowledge that B has answered the call.
9 Now A and B exchange voice media (talk).
10After talking, A hangs up and sends a BYE request.
11B replies with an OK response confirming receipt of the BYE request and the call is
terminated.
11.1.5 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.
Table 53 SIP Call Progression
A B
1. INVITE
2. Ringing
3. OK
4. ACK
5.Dialogue (voice traffic)
6. BYE
7. OK