Push *69. Dial 1169 on a rotary phone.

If you press *69  and the line is busy, you will hear ringing and then a message that tells you that the number is busy. Hang up. If the number becomes free in the next 30 minutes, your phone will ring you back with a special ring. When you pick up the phone, you will be put through to the party you called. (You can still make and receive calls during this callback period; however, Automatic Callback will ring back only if your line is free.)

NOTE: Automatic Recall may or may not be work  in an area not served by Automatic Recall. A recorded message will tell you that your call cannot be completed. For all calls placed using this service, local and long-distance charges may apply. For long-distance calls outside your service area, your long-distance carrier must also be equipped with this technology.
TO CANCEL AUTOMATIC CALLBACK RINGBACK REQUESTS:
 

Push *89. Dial 1189 on a rotary phone.

A recorded message confirms your cancellation.
IMPORTANT FEATURES:

Automatic Recall only returns incoming calls. Use Automatic Callback to return the last call you made.

Automatic Recall only returns the last incoming call you received, whether you answered the call or not.