Yealink SIP-T2 SERIES Administrator's Manual page 231

Don't modify the item on the left of the equal sign.
3. Save the keypad input method file and place it to the provisioning server (e.g.,
192.168.10.25).
4. Specify the access URL of the custom keypad input method file in the configuration
files.
Note
When adding new characters for the existing input method, ensure that the added
characters are supported by IP phones.
The IP phones can only recognize the keypad input method files uploaded using Unicode
encoding.
Do not rename the keypad input method filename.
Procedure
Specify the access URL of the custom keypad input method file using the configuration
files.
Configuration File <y0000000000xx>.cfg
Configuring Basic Features
Specify the access URL of the
custom keypad input method file.
Parameter:
gui_input_method.url
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