1.

  When a line is busy, hang up. 

2.

  Pick up the receiver.

3.

  Press *66.  

4.

  Hang up.

5.

  The busy line will be monitored for up to 30 minutes and you will be notified by a special ringing when the line is free.

6.

  Pick up the receiver and your call will go through.

Busy Call Return will cancel itself automatically after 30 minutes if the line is still busy.