Sip Components; Sip Reports - 2N VoiceBlue Lite User Manual

5.2. SIP Components

SIP reports are transmitted between the following components:
• UAC (User Agent Client) – a terminal Client that initiates SIP
signalling;
• UAS (User Agent Server) – a terminal Server that responses to
SIP signalling from a UAC;
• UA (User Agent) – a SIP network terminal (SIP telephone, or
gateway to other networks), contains a UAC and UAS;
• Proxy server – receives connection requests from a UA and
transfers them to another Proxy server if the particular station
is beyond its control;
• Redirect server – receives connection requests and sends them
back to the requester including destination data instead of
sending them to the calling party;
• Location server – receives registration requests from the UA
and updates the terminal database with them.
All server sections (Proxy, Redirect, Location) are typically
available on a single physical machine called Proxy server, which
is responsible for client database maintenance, connection
establishing, maintenance and termination, and call directing.
The 2N - VoiceBlue Lite gateway is always a UA (has the same
functions as a VoIP telephone), i.e. receives call requests and
directs calls to GSM networks according to the internal LCR.
There are no SIP-defined server sections in the 2N - VoiceBlue
Lite gateway.

5.3. SIP Reports

Here is a list of main signalling reports sent in the SIP
environment:
• INVITE – connection establishing request;
• ACK – acknowledgement of INVITE by the final message
receiver;
• BYE – connection termination;
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