IPhone speakerphone as input when connected to bluetooth?

[amm229]

I am working on a simple hands-free bluetooth solution for calls in my car and am having an issue:

Goal: I want to achieve hands-free bluetooth in a car without built in bluetooth capability but with an aux-in available hidden underneath center the console.

My solution: I purchased a dashboard mount for my IPhone and an aux-to-bluetooth adapter which acts as a bluetooth receiver. The connection works well and I can hear my caller's audio through my cars speakers as desired. However, my voice / input is going through the built-in microphone of my aux-to-bluetooth adapter. Since my actual aux input is located under my center console, the sound is extremely muffled and not usable.

Since my iphone is mounted on my dashboard, my iphone built in speaker would work fine as a mic/input. However, I am not able to configure my phone to output incoming audio from my caller through the bluetooth-aux while using the speakerphone mic on my iphone as input. I can either use iphone for both audio output and input or bluetooth for both audio output and input.

I went looking for an aux-to-bluetooth without a built-in mic as a possible solution but this does not appear to exist.

Any advice?

Thanks in advance!
-Andrew