For those having trouble doing ##3424 on a dialer that doesn't support those codes, there is a workaround. Here's how I did it.
I used the program
QuickMenu. Once you have it installed, click Start, QuickMenu, and there should be a option that says "Execute" or something similar. It may also not be under QuickMenu, I can't remember exactly and I don't have it installed right now, but it is somewhere under Start. From there, browse to
dmrouter.exe. Select that, and in the parameter field, type
/DIAG.
So, your top field should look like this:
\windows\dmrouter.exe
And the bottom field should look like this:
/DIAG
Once you have that, execute it, and it should put your phone into DIAG mode. Then, when you need to get out of DIAG mode, follow the same steps above then exit.