How do I adjust the ringing volume or ring tone on BCM? 

To adjust the ringing volume:

With the telephone free of calls and the handset on the rest press Feature *80, the telephone should now ring, you can adjust the volume by pressing the volume bar under the keypad on the left or right. 

Pressing digits 1, 2, 3 or 4 while it is ringing will also change the ring type.