Yealink T27P Administrator's Guide

Administrator’s Guide for SIP-T2_Series_T4_Series IP Phones
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SIP session timers T1, T2 and T4 are SIP transaction layer timers defined in RFC 3261.
Timer T1 is an estimate of the Round Trip Time (RTT) of transactions between a SIP client
and SIP server. Timer T2 represents the maximum retransmitting time of any SIP request
message. The re-transmitting and doubling of T1 will continue until the retransmitting
time reaches the T2 value. Timer T4 represents the time the network will take to clear
messages between the SIP client and server. These session timers are configurable on IP
phones.
Procedure
SIP session timer can be configured using the configuration files or locally.
Configuration File
<MAC>.cfg
Configure SIP session timer.
Parameters:
sip.timer_t1
sip.timer_t2
sip.timer_t4
Local
Web User Interface
Configure SIP session timer.
Navigate to:
http://<phoneIPAddress>/servlet
?p=settings-sip&q=load
Details of Configuration Parameters:
Parameters
Permitted Values
Default
sip.timer_t1
Float from 0.5 to10
0.5
Description:
Configures the SIP session timer T1 (in seconds).
T1 is an estimate of the Round Trip Time (RTT) of transactions between a SIP client
and SIP server.
Web User Interface:
Settings->SIP->SIP Session Timer T1 (0.5~10s)
Phone User Interface:
None
sip.timer_t2
Float from 2 to 40
4

Yealink T27P Specifications

General

Wall Mountable	Yes
Local Phonebook	1000 entries
Bluetooth	No
Wi-Fi	No
Gigabit Ethernet	No
Display	3.66" 240x120 pixel graphical LCD with backlight
Audio Features	HD voice, Full-duplex speakerphone
Network	Dual-port 10/100 Ethernet switch
Protocols	SIP v1 (RFC2543), v2 (RFC3261)
Power	IEEE 802.3af PoE
Connectivity	2 x RJ45 10/100M Ethernet ports
Voice Codecs	G.711(A/μ), G.722, G.723, G.729AB, G.726
EHS	Supports EHS with Plantronics headsets
Headset Port	Yes
Power Adapter	5V DC (optional)