Volvo S60R Owner's Manual page 211

Telephone (option)
Call options
SMS
A single two-tone signal indicates that you
have received an SMS message.
Volume
Raise the volume with the (+) button in the
steering wheel keypad. Lower the volume
with the (–) button.
When the telephone is activated, the steering
wheel keypad only controls the telephone
functions.
If you wish to adjust radio settings using
these buttons you must first deactivate the
telephone, see page 206.
210