Yealink SIP-T21 - Manual (Page 135)

Troubleshooting
125
To import the phone configurations via web user interface:
1. Click on Settings->Configuration.
2. Click Browse to locate a configuration file from your local system.
3. Click Import to import the configuration file.
Note
How to upgrade firmware?
To upgrade firmware via web user interface:
1. Click on Settings->Upgrade.
2. Click Browse to locate the firmware from your local system.
3. Click Upgrade to upgrade the firmware.
The web user interface prompts “Firmware of the SIP Phone will be updated. It will
The file format of configuration file must be *.bin.