Yealink SIP-T21 E2 Administrator's Guide

Troubleshooting
993
 Ensure that the power is on and the network is available in the process of upgrading.
 Ensure that the web browser is not closed or refreshed when upgrading firmware via web
user interface.
How can I verify the firmware generation and version of the phone?
Press the OK/√ key when the IP phone is idle to check the firmware version. For example:
28.81.0.20.
Item
Description
1
28
Firmware ID.
The firmware ID for each IP phone model is:
 70: SIP-T54S/T52S
 35: SIP-T48G
 28: SIP-T46G
 66: SIP-T48S/T46S/T42S/T41S
 29: SIP-T42G
 36: SIP-T41P
 54: SIP-T40P
 76: SIP-T40G
 46: SIP-T29G
 45: SIP-T27P
 69: SIP-T27G
 44: SIP-T23P/G
 52: SIP-T21(P) E2
 53: SIP-T19(P) E2
 37: CP860
 78: CP920
2
81
Firmware generation.
Note: The larger it is, the newer the firmware
generation is.
3
0
A fixed number.

Yealink SIP-T21 E2 Specifications

General

Brand	Yealink
Model	SIP-T21 E2
Category	IP Phone
Language	English