Bluetooth stereo adapters...need help!

Palmetto Fellow

Android Expert
I would like an A2DP enabled bluetooth device.

I really like the Jabra BT3030 and have found OEM knockoffs for $20. In learning more about them, I have come to discover that like most of the devices like the BT3030 ( Jabra BT3030 Bluetooth Stereo Headset: Cell Phones & Accessories) have a microphone built into the device for the handsfree phone operation.

I would prefer to have the device work opposite a corded headset which uses the microhone on the headset instead of the microphone on the bluetooth adapter. It's been many years since I dabbled in corded headsets...are they all proprietary? Is that why all these devices have their own mics?