The feature that will do what you're wanting is called Trunk Service. The earliest versions of the TVS/TVM did not have it. Since I don't know what version you have, the easiest way to tell is to go into the Port/Trunk Service menu and see if the option is listed. If so, enter the line number under trunk group number, then select the company greeting and CS menu (under incoming call service) that you want to serve that line. Other than recording the greetings and setting up the CS menu that's all there is to it.