ADS-C
I think you are referring to ADS-C.
ADS - C ( contract ) sends position reports at certain waypoints to ATC or the airlines operations center, when a contract is in place. The contract is initiated by the ground side, and cannot be changed by the air side.
ADS - B (broadcast) on the other hand, sends out position and velocity approximately twice a second. ADS-B reports have no addressee, anyone can receive them.
To my knowledge no position reports were sent out automatically prior to the introduction of ADS - C.
ATCast