I just installed a Z2 and the blue tooth phone connects fine but the mic volume is bad at best (sound like you are in a tunnel), there is no echo, but you cannot use it for calls because everyone says they cannot hear you. I have tried several locations for the mic and also tried another mic, but nothing seems to work.

 

At times it works great, then just goes into "tunnel mode". I have tried several other phones and they all have the same problem on the system.

 

Any ideas?

I had a similar issue. People were complaining I sounded far away & in a tunnel. I later found out the quality went way up when i plugged my phone into the car charger. No one complains at all.

 

If you're already plugged in and still have issues, i'd get a new mic.