User's Manual Part 2

Chapter 10 The VoIP Account Screens
BM2022w User’s Guide
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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
[e-mail]
, 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.
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 91 SIP User Agent
SIP Proxy Server
A SIP proxy server receives requests from clients and forwards them to another server.
In the following example, you want to use client device A to call someone who is using client device
C.
1 The client device (A in the figure) sends a call invitation to the SIP proxy server (B).
2 The SIP proxy server forwards the call invitation to C.
Figure 92 SIP Proxy Server
AB
A
C
B
1
2