Just for any future searcher:
Setting the ring tone of the telephone module
Incoming calls are signalled acoustically on the telephone module. There are ten ring tones to choose from:
1. Connect the mobile phone with the telephone module or insert the SIM card into the telephone module. Please refer to "Connecting the mobile phone with the telephone module" or "Telephone module in SIM card mode".
2. Make sure that there is network reception.
3. Enter 0005 on COMAND and press the s button.
4. Select a ring tone for the telephone module via the buttons 0 to 9 on COMAND or the audio system.
5. Press the # button to confirm the selected ring tone.