ZyXEL Communications V501-T1 - Manual (Page 186)

Chapter 11 SIP Account Setup
V500 Series User’s Guide
186
SIP Identities
A SIP account uses an identity (sometimes referred to as a SIP address). A complete SIP
identity is called a SIP URI (Uniform Resource Identifier). A SIP account's URI identifies the
SIP account in a way similar to the way an e-mail address identifies an e-mail account. The
format of a SIP identity is SIP-Number@SIP-Service-Domain.
SIP Number
The SIP number is the part of the SIP URI that comes before the “@” symbol. A SIP number
can use letters like in an e-mail address ([email protected] for example) or numbers
like a telephone number ([email protected] for example).
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.
SIP Call Progression
The following figure displays the basic steps in the setup and tear down of a SIP call. A calls
B.
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.
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.
Table 109 SIP Call Progression
A B
1. INVITE
2. Ringing
3. OK
4. ACK
5.Dialogue (voice traffic)
6. BYE
7. OK