In this setup, all phones are connected to the same ACU and PC; that is, they are all controlled by the same instance of TEMS Investigation. Calls are made between phones in this set.

Another possibility is to have phones that call each other controlled by different PCs, which may reside in separate locations. Each PC runs its own instance of TEMS Investigation and has its own ACU, to which the phones it controls are connected. Below is one example of such a configuration.

Finally, in the mobile-to-fixed configuration, phones connected to a single ACU and PC are used to call fixed-line subscribers, for example, a CallGenerator.