I have iPhone 3GS 16GB Black. I got it unlocked from a local shop. I was using my local sim card normally. Even the edge connectivity was working fine. My guess is he used Blacksn0w to unlock it since I could see it in the installed applications list in Cydia. Now I out of curiosity reinstalled blacksn0w & it showed a couple of error messages & locked my iphone back. It started showing me a message that the sim is invalid.

So I uninstalled blacksn0w & reinstalled it. This time it installed properly, took a little while but fortunately unlocked my phone again. Everything on the phone is working absolutely normally. Now I am again able to use the local sim card but whenever i connect it to itunes, it shows a message that the sim card is invalid & i need to insert AT&T sim to activate the phone. As such i am not able to sync my phone at all.

Any suggestions how to fix it.