Before you do anything else read this link. Also make sure the SIM is properly seated if all your getting is SOS. You should also pull the battery to reload the OS clean to insure all services are reset.
How do I determine if my BlackBerry is "unlocked"? - BlackBerryFAQ
What you should have followed to unlock the BB
http://www.blackberryfaq.com/index.p..._BlackBerry%3F