Dynamic call-blocking algorithms for telecommunications networks

Mass-calling events can cause significant congestion in the phone network due to the high volume of redial attempts. This letter presents dynamic algorithms which randomly block some calls at their origination points, thus reducing traffic in the network. The algorithms respond to changing congestion levels by observing whether or not previous calls have been answered. The algorithms reduce call attempts by 50% during periods of 80% blocking, with little disruption in blocking levels to the dialing customers (blocking increases by less than 1%). We also derive an improved blocking heuristic which is more effective under periods of heavier congestion.