ll who are facing this problem just do these simple steps..
no need to jailbreak or flash etc..i was stuck with same problem...
finaly i got it from other forum..
What U have to Do::..
just sit on it for a while and follow steps..
All you need to remove the previous activation, for that you need to follow the below procedures.
Install OpenSSH in you iphone using Cydia (search for OpenSSH)
Install WinSCP for Windows (WinSCP :: Download)
Use WinSCP to connect to iPhone
Windows Guide To Using WinSCP With iPhone
Follow the below steps:
Download patched lockdownd file from here
RapidShare: Easy Filehosting
Navigate to to /private/var/root/Library/ and copy lockdown folder to your desktop (for backup just in case - this you need to do)
Delete that folder from phone
Unzip downloaded patched file and upload to phone to replace the folder you just deleted
Naviagte into patched folder and make sure file pemissions are set to 644 for all files (follow the procedure in Step 3 above)
Reboot phone.With any sim..(As fone is already unlocked)
enjoy all sims..