i recently bought a new iphone 4s factory unlocked. in order to avoid sim failures and invalid sim errors or No service errors, Each phone has to be unlocked by connecting it to the Itunes.
Kindly follow the below steps to avoid any SIM card conflicts
iPhone FULL Unlock - How it Works:
-Connect your iphone to itunes without any network sim inside and when connected click on the iphones name.
- Click Restore install latest version of iTunes on your Pc or Mac or click check for updates
- Let itunes Backup your phone and then Flash to the Latest Version.
- Now disconnect phone and reconnect after 10 seconds.
- Now Enter another network simcard that's not the same network its locked on to
- Connect phone to iTunes with not accepted (not valid) simcard
- Wait until iTunes detects the phone
- iTunes will display (Congratulations, Your iPhone is now unlocked)
- Phone Unlocked
- just follow the instructions about activating the Iphone.
and iphone is unlocked
NOTE : This is the only FULL LIFE TIME UNLOCK solution for Apple iPhone as the IMEI is registered as UNLOCKED in Apple database.
This solution should be used ONLY THOSE WHO BOUGHT FACTORY UNLOCKED iPHONE 4S.
Your phone will always be unlocked even after each new update of your phone firmware !
All reasons given like bad IMEI series, manufacturing defects etc blah blah are not logical as everything was tested before every sale.