A system and method for monitoring congestion in a communication system including an external packet switched network. The communication system includes a plurality of interconnected host devices, such as base stations, consoles, zone controllers. To determine the presence of congestion on links between a pair of host devices, a series of sequential packets are transmitted between the pair. The sequentially transmitted packets are then monitor fluctuations in transmission delays and lost packets. These two criteria are used to identify congestion levels present on the various links in the communication system, and communications on the relevant interzone link are controlled based on the identified congestion level.