I was trying to use GPRS via a Nokia 6310i from an iPAQ 4150 over BT. I had it all working from the 4150, but the desktop BT could not see the phone (ver. 5.22). Nokia suggested to get the phone firmware upgraded to 5.51, which I did, and now the desktop is working over BT+GPRS, but the 4150 is unable to connect!

The phone is fine using WAP and also GPRS from the desktop, but now gives an error "subscribe to GPRS first" when attempting a connection from the iPAQ. I have seen a number of other people reporting this behaviour.

To cut a long story short, here is the solution:

The 4150 (and probably all WM2003 PPCs) uses an init string of ATE0V1&C1&D2 which used to work under Nokia firmware 5.22 but stops working at 5.50 on.

The laptop BT modem driver (IVT BlueSoleil) uses a slightly different string: AT&FE0V1&D2S0=0S7=10 which clearly works on my laptop.

On the PDA, this is located in the registry at HKLM\Drivers\Unimodem\Init\2 and can easily be changed by a registry editor. After this change, GPRS is working flawlessly!

Now if only someone had a proper VPN client...

Enjoy.