You can't unlock without jailbreak. I think there is a program that can tell you which firmware and baseband you have given your situation but I can't remember the name of it.
If you have a sim that the phone is locked to you can activate the phone in iTunes and find out the firmware and baseband form the phones settings menu...
I have been to 5 professional unlockers. They all said the same thing - the phone requires activation before it can be unlocked. I have ordered a PAYG Spanish SIM from ebay. Waiting for it to arrive.