Nigel,
I'm assuming you are running the MS BlueTooth stack correct? If this is the case, perhaps someone else can help you with this, as the MS stack is not even on my device.
I installed the Widcomm BT stack. While not for everyone, I believe this stack is quite superior, and I have not looked back.......well maybe for the A2DP portion, but thats another story.
After reading your post, I attempted this (for the first time) with my device. I was able to get the phone to connect, and it sent a number to my phone (Verizon Wireless Moto V3c) It started to dial, but it was treating it as a Data call, and immediately ended the connection after about 1 ring. Which seems odd....maybe its just my phone and yours will dial differently?
So I dont know if you want to check it out? Its as simple as downloading the cab file for the BT stack. It comes with an uninstaller as well, so if you dont like it, you can revert right on back to what you've had. I believe it will also keep the existing partnerships for you (if you choose to revert back, but will have to partner again for the widcomm stack).
http://www.aximsite.com/boards/showthread.php?t=122247
There is the link to download.
I think there is something else you may need to download for the wi-fi and BT to "coexist" at the same time, but i'm not sure as i dont see anything about it in that post. Please note that does not mean you cant have wifi and BT on your machine at the same time, just not runing both simultaneously for some things....