[Touch HD Windows Mobile ROM Development] abwyatt:
:D Because that was not the root cause ...

Actually the cause of the so called problem is a lack of understanding of the basic WM and HTC data connection settings and more specifically the way the two operate together, or don't in this case. In fact there really is no problem and nothing specific to the WM6.5 ROMs. This auto data connection behavior existed in my stock WM6.1 ROM way back in the dim old days.

Let me try to explain it this way.

First thing to understand is that there are two controls for Data Connection. A HTC TF3D/Sense one which everyone knows as Comm Manager. The second deeper level one is the WM6.X one which you will find at Settings > Connections > Connections > Advanced > Select Networks > Your Cellular Operator Settings (GPRS Settings).

The second thing to understand is that when you do a hard reset as you must when you flash a ROM, the Auto Connection Setup process will automatically select for you and set the GPRS settings on by default. So, deep down there, WM6.x has set you up to use a data connection automatically whenever your mobile needs a data connection and your WiFi is disabled. This happens for example if your email is set to auto download every so many minutes. Remember, email is a WM6.X service.

The third thing to understand is that the HTC Comm Manager really only controls data connections from the HTC interface, ie. TF3D/Sense. For example, if you do a weather update, this is a TF3D/Sense service. So if you turn off Data Connection in Comm Manager it will just turn off data connections to the interface. But lets say your email does an auto send and receive, because the WM6.X GPRS setting is enabled, a data connection will take place regardless of what you did in the Comm Manager.

So how to get around this problem? Easy! Go to the WM6.X setting for Connections that I pointed out above. After entering 'Select Networks' use the drop down box to select 'My Work Network' in the upper setting for programs that automatically connect to the internet. This will totally disable your data connection and it will not turn on again until you do the reverse.

Now, to turn data back on, you don't need to go into WM settings. You will find that the Comm Manager is sort of connected to the WM6.X setting. Turn on Data Connection in Comm Manager and you will find that it brings up the WM6.X Connections settings so that you can go to the drop down box and re-enable your Cellular operator's settings for GPRS. After clicking OK a few times you will end up back at Comm Manager where you turn on Data Connections. If you skip this last step, it will turn on automatically anyway when a program calls for a data connection.

Now the quirk is that Comm Manager is not connected to the WM6.x settings in the same way when you want to turn Data Connection off in Comm Manager. In other words it does not take you back to the WM connection settings when you turn it off as it does when you turn it on. As I showed you above, you have to do it the long winded way and dig deep into WM6.x Connection settings to turn off your cellular data connection. Yes sure, Comm Manager could definitely have been better built in this regards. But it has been like this since day 1.

Programs such as NoData which some chefs cook into their ROMs provide shortcuts to reach those deep WM Connections settings. But frankly, once you know where to find the settings, it becomes second nature and I have never had the need to use NoData.

Anyway, hope this helps.