ZyXEL Communications P-2302HWL-P1 Series - Manual (Page 140)

P-2302HW/HWL-P1 Series User’s Guide
140 Chapter 9 SIP
9.1.3.2 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.
9.1.4 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.
3 B sends a response indicating that the telephone is ringing.
4 B sends an OK response after the call is answered.
5 A then sends an ACK message to acknowledge that B has answered the call.
6 Now A and B exchange voice media (talk).
7 After talking, A hangs up and sends a BYE request.
8 B replies with an OK response confirming receipt of the BYE request and the call is
terminated.
9.1.5 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 59 SIP Call Progression
A B
1. INVITE
2. Ringing
3. OK
4. ACK
5.Dialogue (voice traffic)
6. BYE
7. OK