After doing a little research, I would assume that my phone that is now back 2.2.1 still has the 3.0 baseband, which is not allowing me to activate.
I found on livecrunch.com a member by the name of Danny posted this:
"For all of those with carrier issues, if you don’t know why that’s happening its because 3.0 updated your baseband, which you cannot change, at least I thought so. I’m posting a link from my iDisk for a custom restore that i created with pwnage tool, this ipsw does not include cydia, or installer, and does not activate your phone, but from what I’ve heard, it is possible to get your baseband down using a custom restore. Try it out and let me know if it works for you or not as I had no need to actually test it myself.
For all of you with a PC please attempt “J’s” method above, for some reason it’s a lot easier to do the whole restore on a PC than a Mac. Anyway, good luck to you all."
Download Link for Danny's ipsw
Other users on the forum:
Here Seem to have had success to downgrade the baseband.
So there is hope, especially for those who live a few hours from a Mac "
Genius". I'm about to try it right now. I'll let you know if I have any success.