Perhaps you thought you did not need to save a certain voicemail message, or maybe you accidentally hit the wrong key and deleted an important message. Frequently, people realize that they need to review or save a voicemail message that they have previously deleted. Retrieving deleted voicemail messages from AT&T mobile phones is possible, but there is a limit to which erased messages you can retrieve within a certain time frame.
Access your voicemail by pressing and holding the "1" key on your AT&T mobile phone.
Press "1" to listen to your current voicemail message.
Press "7" to delete your message. If you decide that you need to retrieve the message either to hear it again or save it, wait for the prompt that begins, "To listen to erased messages..."
Press the "1" key and then the "9" key directly after it. Listen to the deleted message.
Press "7" to permanently delete the message or "9" to save it in the archives.
If you delete a message and then disconnect the call, the message will be deleted permanently, and there is no way to retrieve it. You must retrieve the message from deletion within the same call in which you deleted the message.