voice control issue with ios4.2.1 and bluetooth iPhone 3G

I am having a problem using a Blueant Supertooth 3 with two different iphone 3gs phones and two different ST3s. Everything worked great until OS4.2.1. I spoke to Blueant and since the ST3 is only a speaker and two way bluetooth there is nothing that can be done on the Blueant side. I also tried turning up the voice control volume with no success. There does not appear to be a legitimate way to revert to an earlier version of the OS. I have done hard resets on both devices with no change. Once the call connects the volume is fine as always. Apparently the tone transmit to the bluetooth is different than the voice transmit.
There was another post for bluetooth earpeices that was listed as answers, but the solution of increasing volume while in voice control does not solve this problem
iphone 3gs iOS 4