ironman We understand that your device can establish an HFP connection and you can hear background hiss, which indicates the underlying Bluetooth connection between the phone and the module is functioning properly.
To further pinpoint the root cause, please assist us by providing the following information:
1.Phone-Side Check: Please confirm that during the call, the phone's audio output is correctly routed to the Bluetooth device. Sometimes, the audio might remain on the phone's built-in earpiece or speaker.
2.UART Log: Please provide a complete UART log capturing the entire process from when the module powers on until you make a call and reproduce the issue. This will allow us to examine the complete communication sequence and all AT command configurations.
