Yes, international usage is an option for the Blackberry. There are plans for this here: http://www.wireless.att.com/learn/international/roaming/affordable-world-packages.jsp
Yes as long as the phone is att and has a sim card slot
no, sprint and Verizon are cmda. att and t-moble are gsm.
You can get it unlocked, available now.
Both, AT&T bought out Cingular.
*3282#
no it does not . it fits into a blackberry 8350I from nextel but it doesnt fit into any tmobile or att.
obviously not. Att uses GSM technology while sprint uses CDMA.
sadly no the black berry storm 2 dose not work on att, but it dose work on the network verizon.
sony xperia, blackberry bold and htc touch pro
I have a Blackberry Storm that is only offered by Verizon. I have unlocked it and am using it on ATT. The best way to do this is to go to www.crackberry.com and go through some of the disucssions there. They have lots of unlocking tips and links. The best one I found was www.berryology.com. This website is all about unlocking Blackberry phones.
stag
The easiest option would be to go to an AT&T corporate location with both phones and have the use the UME or universal memory exchanger to transfer contacts. Call customer care at 800-331-0500 for the nearest store and call the store to make sure they have a UME.