Session Timer - Yealink SIP-T5 Series Administrator's Manual

Parameter sip.timer_t1
Description It configures the SIP session timer T1 (in seconds).
Permitted
Float from 0.5 to 10
Values
Default 0.5
Web UI Settings > SIP > SIP Session Timer T1 (0.5~10s)
Parameter sip.timer_t2
Description It configures the SIP session timer T2 (in seconds).
Permitted
Float from 2 to 40
Values
Default 4
Web UI Settings > SIP > SIP Session Timer T2 (2~40s)
Parameter sip.timer_t4
Description It configures the SIP session timer T4 (in seconds).
Permitted
Float from 2.5 to 60
Values
Default 5
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
<y0000000000xx>.cfg
<y0000000000xx>.cfg
<y0000000000xx>.cfg
RFC 4028. The phones support two refresher modes: UAC and
General Features
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