ZyXEL Communications MAX318M2W, User Manual

Page: 140 / 294

Chapter 10 The VoIP Account Screens
MAX318M2W User’s Guide
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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 (johndoe@your-ITSP.com for
example) or numbers like a telephone number (1122334455@VoIP-provider.com
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
1122334455@VoIP-provider.com , then “VoIP-
provider.com” is the SIP service domain.
SIP Register Server
A SIP register server maintains a database of SIP identity-to-IP address (or
domain name) mapping. The register server checks your user name and password
when you register.
10.1.3 SIP User Agent
A SIP user agent can make and receive VoIP telephone calls. This means that SIP
can be used for peer-to-peer communications even though it is a client-server
protocol. In the following figure, either A or B can act as a SIP user agent client to
initiate a call. A and B can also both act as a SIP user agent to receive the call.
Figure 66 SIP User Agent
SIP Proxy Server
A SIP proxy server receives requests from clients and forwards them to another
server.
A B