Yealink SIP-T48G User Manual page 173

(Optional.) Enter the no answer forward on code or off code respectively in the
4)
On Code or Off Code field.
You can also activate no answer forward for all accounts. Do the following:
Tap the All Lines soft key.
1)
The touch screen prompts "Copy to all lines?".
Tap OK to accept the change or Cancel to cancel.
2)
Tap the Save soft key to accept the change.
5.
Basic Call Features
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