UC2000-VE/F/G GSM/CDMA/WCDMA VoIP Gateway User Manual
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Shenzhen Dinstar Co., Ltd.
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183 Mode
Immediately: Gateway will send "183 RING" immediately to SIP Server while it
receive “INVITE". In this situation, the called party possibly still not in ringing status.
Alerted: Gateway will send "183 RING" after received exact ringing signal from
GSM/CDMA network. In this situation, the called party is definitely in ringing status.
Session Timer
SIP Session Timers which is an extension of SIP RFC 4028 that allows a periodic
refreshing of a SIP session using the RE-INVITE/UPDATE message. The refreshing
allows both the user agent and proxy to determine if the SIP session is still active. The
SIP Session Timer is a keep alive mechanism for SIP sessions that allow User Agents
(UA) or proxies to determine the status of a session and to release it if it is not active,
even if a BYE has not been received.
Session timer Interval
The initial INVITE request establishes the duration of the session and may include a
Session-Expires header and a Min-SE header. These headers indicate the session
timer value required by the user agent (UAC).
A receiving user agent server (UAS) or
proxy can lower the session timer value, but not lower than the value of the Min-SE
header. If the session timer duration is lower than the configured minimum, the proxy
or UAS can also send out a 422 response message. If the UAS or proxy finds that the
session timer value is acceptable, it copies the Session-Expires header into the 2xx
class response.
A UAS or proxy can insert a Session-Expires header in the INVITE if the UAC did not
include one. Thus a UAC can receive a Session-Expires header in a response even if
none was present in the request. Its value range from 90-60000s.
Session Timer Refresher
It specifies refresher which including in SIP message body, user agent client (UAC) or
user agent server (UAS).
UPDATE sips:[email protected] SIP/2.0