Can be played with mouse only. The city can also be navigated using WASD and QE to orbit.
The in-game tutorial mentions that you can send tapes to people. When you have this option (after you call someone using the phonebook), the option is printed on the screen - it says <TAPES ACCEPTED>. When you see this, you can press the TAPE button, select a tape using the previous / next buttons, preview it using the play button, and send it using the check button.