Yealink SIP-T27G Administrator's Guide

General Features
496
Parameter
sip.timer_t1 <y0000000000xx>.cfg
Description
It configures the SIP session timer T1 (in seconds).
Permitted
Values
Float from 0.5 to 10
Default
0.5
Web UI
Settings > SIP > SIP Session Timer T1 (0.5~10s)
Parameter
sip.timer_t2 <y0000000000xx>.cfg
Description
It configures the SIP session timer T2 (in seconds).
Permitted
Values
Float from 2 to 40
Default
4
Web UI
Settings > SIP > SIP Session Timer T2 (2~40s)
Parameter
sip.timer_t4 <y0000000000xx>.cfg
Description
It configures the SIP session timer T4 (in seconds).
Permitted
Values
Float from 2.5 to 60
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 RFC 4028. The phones support two refresher modes: UAC and
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

Yealink SIP-T27G Specifications

General

Mounting	Desk/Wall
Handset type	Wired handset
Product type	IP Phone
Product color	Black, Gold
Wall mountable	Yes
Display diagonal	3.66 \
Display resolution	240 x 120 pixels
RJ-9 ports quantity	2
USB 2.0 ports quantity	1
Voice codecs	CNG, G.711, G.722, G.723.1, G.726, G.729, G.729ab, VAD, iLBC
Dual-Tone Multi-Frequency (DTMF) modes	SIP info
Lines quantity	8 lines
Phonebook capacity	1000 entries
Number of VoIP accounts	6
Bluetooth	-
Security algorithms	AES, MD5
Networking standards	IEEE 802.1Q, IEEE 802.1p, IEEE 802.1x, IEEE 802.3af
Ethernet LAN interface type	Gigabit Ethernet
Volume control	Digital
Operating temperature (T-T)	-10 - 50 °C
Operating relative humidity (H-H)	10 - 95 %
Cables included	LAN (RJ-45)
Number of handles included	1 pc(s)
Harmonized System (HS) code	85171800

Weight and Dimensions

Depth	210 mm
Width	265 mm
Height	170.5 mm