It can be UNLOCKED from the Network lock if it locked to GSM network,It cannot be Unlocked from the Network lock if it locked to CDMA Network,I have Unlocked my I-Phone and Jailbreak it.It's version 4,You can get the remote Unlock service from here
Onlinegsmunlock and Unlock the Phone from the Network Lock,then You need to specify current Network and Country it locked,All network locked Phones cannot be Unlocked,only some Network Lock can be UNLOCKED remotely there.....then you can Jailbreak the Phone here
Iphone4jailbreak