Unanswered calls aren't going to voicemail. Instead the caller gets the message that the call cannot be completed as dialed.

Hi @texassunshine47,

We understand that you are concerned about voicemail issue, and we are here to help you out. Your phone needs a wireless connection to receive calls, access voicemail, download Visual Voicemail messages, and get voicemail notification alerts. To check that your signal is strong enough for this:

1. Turn your phone off for 10 seconds and then back on.
2. Place a test call to 611.
3. Do one of the following:
   • If the test call is successful, press and hold 1 to dial into the voicemail system.
   • If your test call fails, confirm you have wireless coverage.
   • If Visual Voicemail won't download, press and hold 1 to check your messages.

If you aren't getting voicemail notification alerts and you aren't traveling outside the AT&T wireless coverage area, see how to turn voicemail notification alerts on and off.

For more information, please check out the ⁠link.

Thank you for visiting Community and Forums,
Hella, Community and Forum Specialist.

It sounds to me like call forwarding is enabled to an invalid number. Check for call forwarding in your phone's settings.