A CTI system includes a translation table of user names against consistent (i.e. simulated) calling line identity. When a user originates a call, the CTI server knows the name of the user currently associated with, i.e. logged on at, the originating work desk, and refers to the consistent CLI translation table to obtain the consistent CLI for that user, and to instruct the switch to make the call using that consistent CLI in the setup signalling message. In some CTI systems, the consistent CLI translation table is in the form of a user-associated dummy terminal translation table, and the CTI server instructs the PBX to make a call from the respective user-associated dummy terminal. In this case, the PBX stores the consistent CLI corresponding to that dummy terminal. Calling users can originate calls from any of the systems work desks, or even from remote telephones, and the system will always deliver a setup signalling message containing the respective consistent CLI allocated to the calling user, thus enabling a return call to be properly delivered or recognized as such.