According to the different structure, divided into the full utilization of the wiring harness, part of the use of the wiring harness and link system; According to the different service mode, divided into the loss of wiring harness and waiting for the wiring harness (see stochastic service System); According to the number of load sources of service, it is divided into infinite load source harness and finite load source harness. In telecommunication system, the equipment which is directly used for communication between users, which is the system of full utilization of the loss of infinite load source, and the equipment used to control the connecting process of the communication equipment, is the infinite load source waiting for the full utilization degree system.
When the number of load sources is not very large, the full utilization system or partial utilization system of the finite load source is generally used. According to the call behavior of the load source, whether the user call fails after the new call attempt, the harness can be divided into duplicate call system and non-repetitive call system. The actual communication system is repeated call, the non-repetitive call system is the approximation of the repetitive call system.