An outbound call consists of a scheduled call and two retries (optional). If a customer/ agent misses a scheduled call, then the OBD will generate another call to the same customer after 3 minutes (this is configurable).
If both the retries fails then there are two possibilities:
If it is a promotional call, then the customer’s phone number cannot be requeued for the next 24 hours.
If it is a transactional call, then the customer’s phone number can be requeued in the contact list again. However there is a upper cap on number of times it can be requeued.