Mr12volt P2000-CICMD Quick User Manual page 6

Bluetooth
 Phone contact list
 Contact history
 Dial Pad
 Audio Streaming
BT Hands-free
 When a call is incoming, answer and reject button will appear on display,
use MMI/i-Drive/Rotary button to select.
 BMW factory Bluetooth HF and Mr12volt Bluetooth can be connected at
the same time. (see below picture) When both are connected and a call is
incoming, BMW HF will take over Mr12volt HF and it can be answered
through phone button on steering wheel.

Mr12volt does not support the integration of OEM microphone even with
the installation of a Y-cable. if you need to use Mr12volt HF or Voice
Command such as Siri, the 3.5mm jack microphone supplied in the
package must be installed.