Try this if your phone fails to ring during incoming calls.
INSTRUCTIONS & INFO
If you are transferring a phone number from a prior provider to the Home Base, it may take up to five (5) days. During that time, you can make calls immediately on your Home Base. However, you must keep a phone plugged into your wall jack to receive calls on your old service until your transfer completes. Check transfer status at att.com/port.
Make sure that your Home Base is NOT connected to your in-home phone wiring.
Make sure that your home phone is powered on and connected to the Home Base.
Dial #21# to turn off call forwarding, if it is currently on.