Session Timer; Session Timer Configuration - Yealink SIP-T3 Administrator's Manual

Administrator's Guide for SIP-T2 /T3 /T4 /T5 /CP920 IP Phones
Web UI Settings > SIP > SIP Session Timer T4 (2.5~60s)

Session Timer

Session timer allows a periodic refresh of SIP sessions through an UPDATE request, to determine whether a SIP
session is still active. Session timer is specified in
UAS. Whether the endpoint functions as a UAC or a UAS depends on the UA that initiates the SIP request. If the ini-
tiator is configured as UAC, the other client or the SIP server will function as a UAS. If the initiator is configured as
UAS, the other client or the SIP server will function as a UAC. The session expiration is negotiated via the Session-
Expires header in the INVITE message. The negotiated refresher is always the UAC and it will send an UPDATE
request at the negotiated session expiration. The value "refresher=uac" included in the UPDATE message means
that the UAC performs the refresh.
Example of UPDATE message (UAC mode):
UPDATE sip:1058@10.10.20.34:5060 SIP/2.0
Via: SIP/2.0/UDP 10.10.20.32:5060;branch=z9hG4bK2104991394
From: "10111" <sip:10111@10.2.1.48:5060 > ;tag=2170397024
To: <sip:1058@10.2.1.48:5060 > ;tag=200382096
Call-ID: 4_1556494084@10.10.20.32
CSeq: 2 UPDATE
Contact: <sip:10111@10.10.20.32:5060 >
Max-Forwards: 70
User-Agent: Yealink SIP-T46G 28.82.0.20
Session-Expires: 90;refresher=uac
Supported: timer
Content-Length: 0
Topic

Session Timer Configuration

Session Timer Configuration
The following table lists the parameters you can use to configure the session timer.
Parameter account.X.session_timer.enable
Description It enables or disables the session timer.
0-Disabled
Permitted
Values
1-Enabled, the phone will send periodic UPDATE requests to refresh the session during a call.
Default
0
Web UI Account > Advanced > Session Timer
Parameter account.X.session_timer.expires
It configures the interval (in seconds) for refreshing the SIP session during a call.
Description
An UPDATE will be sent after 50% of its value has elapsed. For example, if it is set to 1800 (1800s),
the phone will refresh the session during a call every 900 seconds.
553
RFC 4028. The phones support two refresher modes: UAC and
[1]
<MAC>.cfg
[1]
<MAC>.cfg