Not getting the digital network? I'm confused... it's a V600i, the only networks it can connect to are GSM networks, which are digital.
In any case... you're basically saying the roaming triangle is always on your phone, right?
You bought an unlocked V600i from somewhere (not Cingular), so it doesn't have a Cingular flex on it (which disables the roaming triangle by default).
This can be fixed. You'll need a data cable for your phone and some free software. You need to do some reading too, so you can educate yourself about what you're going to do... http://xlr8.us/hofo/
The specific change you want to make is to seem 0032, offset 34, bit 3. It controls the roaming triangle. And you want to turn it off.