AT&T offers home phone service in conjunction with its more popular wireless phone service. In addition to offering the actual phone service, AT&T also sells telephone accessories, including answering machines. The answering machine is usually built into the cordless phone base and allows you to save messages from missed callers for a later review. The initial setup of the machine requires that you record an outgoing message for your callers to hear when the answering machine picks up.
Press the "Menu" key on the telephone base. Select "Answering System," then select the mailbox you'd like to set up.
Select "Announcement," click "Annc audio," and then click "Record."
Record the outgoing message at the prompt, speaking directly toward the microphone in the base of the telephone. Press the "Stop" button when you are done.