This app is almost $7. There is another app Auto Redial that is $1 that only redials dropped calls. The $7 Auto Redial Pro will allow customization of redialing busy numbers and notify once a connections is made but will it do the same thing as the $1 app?
The vendor support states that the Pro version only works in cases in which there is a busy signal for the redialing. The redial after a dropped call is not handled by the Pro but has been added to their list of possible updates.