Appendix L SIP
335
Nortel Business Secure Router 252 Configuration — Advanced
SIP Servers
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.
SIP User Agent Server
A SIP user agent server 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
Figure 160
, 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 server to
receive the call.
Figure 160
SIP User Agent Server
SIP Proxy Server
A SIP proxy server receives requests from clients and forwards them to another
server.
In the following example, client device A calls 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.
Summary of Contents for 252
Page 14: ...14 Contents NN47923 501 ...
Page 20: ...20 Figures NN47923 501 ...
Page 24: ...24 Tables NN47923 501 ...
Page 30: ...30 Preface NN47923 501 ...
Page 42: ...42 Chapter 1 Getting to know your Nortel Business Secure Router 252 NN47923 501 ...
Page 48: ...48 Chapter 2 Introducing the SMT NN47923 501 SMT menus at a glance Figure 6 SMT overview ...
Page 72: ...72 Chapter 3 WAN and Dial Backup Setup NN47923 501 ...
Page 80: ...80 Chapter 4 LAN setup NN47923 501 ...
Page 84: ...84 Chapter 5 Internet access NN47923 501 ...
Page 98: ...98 Chapter 6 Remote Node setup NN47923 501 ...
Page 102: ...102 Chapter 7 IP Static Route Setup NN47923 501 ...
Page 130: ...130 Chapter 9 Network Address Translation NAT NN47923 501 ...
Page 156: ...156 Chapter 12 SNMP Configuration NN47923 501 ...
Page 178: ...178 Chapter 14 System information and diagnosis NN47923 501 ...
Page 198: ...198 Chapter 15 Firmware and configuration file maintenance NN47923 501 ...
Page 212: ...212 Chapter 17 Remote Management NN47923 501 ...
Page 232: ...232 Appendix B Triangle Route NN47923 501 ...
Page 252: ...252 Appendix D PPPoE NN47923 501 ...
Page 256: ...256 Appendix E Hardware specifications NN47923 501 ...
Page 266: ...266 Appendix F IP subnetting NN47923 501 ...
Page 308: ...308 Appendix H NetBIOS filter commands NN47923 501 ...
Page 332: ...332 Appendix K Brute force password guessing protection NN47923 501 ...