14 • VoIP Protocol
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snom technology AG • 15
The SIP
Architecture
This paragraph is intended to serve only as a basic introduction to
the SIP world. for more detailed information please refer to the available
literature on this topic.
User Agents
User agents play a central role in SIP. They are normally the
endpoints of the communication. Typical examples for a user agent are
telephones, gateway and media servers.
User agents typically fulfill the following tasks:
• they play and record audio,
• they compress and uncompress the digital audio,
• they do echo compensation if there is a need for this,
• they compensate for packet jitter and packet loss,
• they look for the destination,
• they retrieve their configuration information,
• they keep track of phones that offer a call pickup,
• they publish their state upon request,
• they determine and publish the probability of finding somebody,
• they terminate one or more identities,
• they redirect calls when nobody picks up,
• they are part of a virtual LAN,
• they search address books (LDAP),
• they search internet addresses (DNS A, DNS SRV),
• they usually include a web server,
• they send an receive instant messaging information,
• they publish network management information (SNMP),
• they behave like normal computers on the network (DHCP, DNS).
2.
Summary of Contents for 4S Media Server
Page 1: ...Administrator s Manual snom 4S SIP Proxy Registrar Version 2 30 ...
Page 14: ...14 VoIP Protocol S N O M 4 S P R O X Y R E G I S T R A R M A N U A L 1 ...
Page 84: ...84 Routing S N O M 4 S P R O X Y R E G I S T R A R M A N U A L 10 ...
Page 98: ...98 Maintenance S N O M 4 S P R O X Y R E G I S T R A R M A N U A L 13 ...