Try resetting your BMW BT module. You do this by waiting until the vehicle "shuts down". Unplug the BT module for about 10 monutes. Its sitting in the drivers side near the NAV unit on the bottom (floor) of the compartment.

If you can validate its function with another MSMobile phone too.

If the phone works fine in one vehicle and not in the other it may be the BMW BT module or antenna (as previously stated).

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E83 - Aero PKG Mods installed: Homelink mirror. CIS-IBUS video module, AUX, Rr Dr Release, stock wheels, Remote start, CarPC (Atom) & mud flaps - NAV - MKIV - NA Map DVD - 2011
E46 - 18.5 wheels/tires (summer), 17 stock (winter), Homelink, NAV software upgrade, BMW video module, Radio to V53, AUX, USB IBUS interface,BMW alarm install, CarPC(Epia), remote starter, tank battery & angel eyes. NAV - MKIII - NA Map CD - High Version 2008.1