Yealink SIP-T48G - Manual (Page 107)

Basic Call Features
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2. When the called party becomes idle, the touch screen prompts the following:
3. Tap the OK soft key to redial the number.
Note
You can tap a call return key to place a call back to the last incoming call.
To configure a call return key via phone user interface:
1. Tap the DSS Key key.
2. Tap the desired line key.
3. Tap the gray box of the Type field.
4. Tap Key Event from the pull-down list.
5. Tap the gray box of the Key Event field.
6. Tap Call Return from the pull-down list.
7. (Optional.) Enter a label that will appear on the touch screen in the Label field.
Call completion is not available on all servers. For more information, contact your system
administrator.