You're right, I guess the correct term is the BT modules ending in '7'. Is it fair to say the module is usually part of a audio/video package on a car, which the dual mic might be a part of?
The thread that I got the '7' lead from is here, for what it's worth:
"I have had this problem from the get-go, with the BT. I joined this forum specifically because I saw Muggsy77's post, and was amazed that so many others have not had the same problem,since it appears to be kind of endemic on various VW forums. A couple of the TDI forums, in particular, have extensive discussions on this topic.
Briefly, my experience has been that outgoing audio intelligibility (from the car) is tolerable if and only if the car is traveling at or below about 30 mph, no windows are open, and the blower is either off or on the lowest setting. If any of these conditions is changed for the "noisier," outgoing audio intelligibility deteriorates very rapidly to actually zero, where I have to drop the BT, and use the phone directly. I've used this under all signal levels, and with two different phones, including an iPhone and an older LG VX8300. Identical symptoms. I don't have the Nav system. There are apparently three versions of the audio/nav/BT interface (I don't recall the p/n prefix, but the versions are 2, 3, and 7). I have the 2 version, I believe. The 7 version (which has the super-zapola MFD, etc) contains the dual-microphone active noise-canceling audio chain, so it's something that VW seems to know about. I agree with the poster who asked to have the mike on the driver's side, for a nice change. I actually go hoarse from trying to shout, at times. It's not the phone or signal atrength, because even voice-dialing is a real challenge, and that's just car-to-phone BT, not involving external signal levels.
I'm with you, Muggsy -- there's something odd going on. I suspect that VW may have switched microphone suppliers in mid-stream, and is reluctant to own up to it, given the recall/retrofit implication. The noise is definitely road noise, as if there is inadequate acoustic isolation of the mike. It's real, and it's a major showstopper for reliable phone use with the car's BT." - Guy with a 2010 Jetta