Try this if your answering machine does not pick up incoming calls.
INSTRUCTIONS & INFO
Set your answering machine to pick up calls in fewer than five (5) rings.
Note: This ensures that your answering machine will pick up calls before network voicemail.
Alternately, the network voicemail settings can be altered. Dial '1' to access voicemail, then follow the voice prompts to increase the number of rings.
To remove network voicemail from your account, contact AT&T Customer Care by dialing 611, or 1-800-331-0500.