AT&T Wireless Home Phone User Manual page 13

Check the Wireless Signal
Raise antenna to an upright position.
Confirm signal strength light is green for optimal performance.
Yellow indicates a moderate signal and may be sufficient.
Note: If you do not see a green light (strong signal), you may
want to choose an alternate installation location.
Place a Test Call
Place a test call from your connected home phone.
Make sure to use 10-digit dialing even for local calls.
Getting Started 7