What's the procedure to switch from iPhone to BB?

First of all pardon me if I make any grammatical errors, English is not my first language.

Greetings all... As of today, January 7th, I am officially a Blackberry user. :D
I purchased a new Blackberry Bold 9000 from a cellphone store in Ghana, West Africa. I reside in the USA however, and the BB, while unlocked, has a "T-Mobile" logo on the bottom. In the states I use a 2g iPhone with the $20 EDGE plan.

My question is this: How would I go about canceling the $20 iPhone plan and replacing it with the $35 dollar Blackberry plan? Also, would I encounter any difficulties due to it being an ex-T-Mobile device? :o

Thanks in advance fellow Crackberry members! :)

I would say you would have to call customor service at AT&T. If the phone is truly unlocked you should have any problems.

^ should not have any problems*