Chapter 15 VoIP
B222s User’s Guide
137
After successful registration, the SIP server knows that the users (identified by their dedicated SIP
URIs) are represented by the UA, and knows the IP address to which the SIP requests and
responses should be sent.
Registration is initiated by the User Agent Client (UAC) running in the VoIP gateway (the LTE
Device). The gateway must be configured with information letting it know where to send the
REGISTER message, as well as the relevant user and authorization data.
A SIP registration has a limited lifespan. The User Agent Client must renew its registration within
this lifespan. If it does not do so, the registration data will be deleted from the SIP registrar's
database and the connection broken.
The LTE Device attempts to register all enabled subscriber ports when it is switched on. When you
enable a subscriber port that was previously disabled, the LTE Device attempts to register the port
immediately.
Authorization Requirements
SIP registrations (and subsequent SIP requests) require a username and password for
authorization. These credentials are validated via a challenge / response system using the HTTP
digest mechanism (as detailed in RFC3261, "SIP: Session Initiation Protocol").
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
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 76
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.
A
B
Summary of Contents for B222s
Page 4: ...Contents Overview B222s User s Guide 4 ...
Page 12: ...Table of Contents B222s User s Guide 12 ...
Page 13: ...13 PART I User s Guide ...
Page 14: ...14 ...
Page 28: ...28 ...
Page 78: ...Chapter 7 Routing B222s User s Guide 78 ...
Page 82: ...Chapter 8 DNS Route B222s User s Guide 82 ...
Page 102: ...Chapter 10 Network Address Translation NAT B222s User s Guide 102 ...
Page 114: ...Chapter 12 Firewall B222s User s Guide 114 ...
Page 120: ...Chapter 14 Parental Control B222s User s Guide 120 ...
Page 125: ...Chapter 15 VoIP B222s User s Guide 125 ...
Page 144: ...Chapter 15 VoIP B222s User s Guide 144 ...
Page 154: ...Chapter 17 Traffic Status B222s User s Guide 154 ...
Page 156: ...Chapter 18 User Account B222s User s Guide 156 ...
Page 170: ...Chapter 24 Backup Restore B222s User s Guide 170 ...
Page 172: ...Chapter 25 Diagnostic B222s User s Guide 172 ...
Page 218: ...Appendix B Setting Up Your Computer s IP Address B222s User s Guide 218 ...
Page 228: ...Appendix C Pop up Windows JavaScript and Java Permissions B222s User s Guide 228 ...
Page 252: ...Appendix E Common Services B222s User s Guide 252 ...