EDITED: (with correct info)

I think you can have up to 4 phones paired with the ULF, dominant phone is the last phone paired (pair slot #4), then in reverse order of pairing.

Only one phone will work at any one time, as the ULF tries to connect to the last phone in order.

eg: your wife has a BT phone paired in #1 pair slot, you have #2, your wife gets in the car first and the starts the car, (her phone then pairs), you then get in the car, and the ULF detects your phone and "sees" that it has a higher pair slot and moves the ULf connection from your wifes phone to your phone.

Only one active connection is possible.

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Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.