Automatic redial is a feature designed to make it easier to dial numbers that are engaged. After the dialled number is found to be engaged, the phone will either repeatedly redial the number automatically, or it can be set to redial by pressing the appropriate key. This feature saves the user from dialling the number many times until a ringing tone can be obtained.
Automatic redial will usually operate for a set number of redials before giving up, to avoid the negative consequences of battery drain, blocking the phone, and causing unnecessary network traffic