Dinstar DWG2000E - Page 62

DWG2000E/F/G GSM/CDMA VoIP Gateway User Manual
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Shenzhen Dinstar Technologies Co., Ltd.
61
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:bob@192.0.2.4 SIP/2.0
Via: SIP/2.0 pc33.atlanta.example.com;branch=z9hG4bKnashds12
Route: sips:p1.atlanta.example.com;lr
Supported: timer
Session-Expires: 4000;refresher=uac
Max-Forwards: 70
To: Bob <sips:bob@biloxi.example.com>;tag=9as888nd
From: Alice <sips:alice@atlanta.example.com>;tag=1928301774
Call-ID: a84b4c76e66710
CSeq: 314162 UPDATE
Contact: <sips:alice@pc33.atlanta.example.com>
Configuring GSM-SIP Mapping Code
This part specifies response codes between GSM cause reason and SIP response code.