Hello, we are designing dual mode bluetooth audio earphones. Audio is streamed via bluetooth classic (like any other earphone), but we can also connect to the earphones via BLE to get some specific sensor data. For information, the earphones are not MFI. We have also developped a special iOS application that should automatically connect to the earphones via BLE (when the user launch the app), if the earphones are connected to the smartphone in bluetooth classic. We are able to find out if the smartphone is connected to our earphones using AVAudioSession.currentRoute.outputs and scan for BLE peripherals to find our earphones BLE peripheral. Yet, I don't know how to make sure that a found BLE peripheral corresponds to the connected Bluetooth classic device. WHat about if two earphones are nearby ? Is there any way to check that, so that our application can automatically connect to the BLE peripheral, without needing the user to select to manually select and connect to it ? I've heard about the Cross Transport Key Derivation in the What's New In Core Bluetooth WWDC session of 2019, but I'm not sure wether this would allow me to do what I want. Thank you for your help