If you have backup of that iPhone in iTunes, you need to
go to Preferences >> Dvices, and the if you hover the
backup you should see not only IMEI number but also
Serial number and Mobile number.
You can check if that IMEI or Serial number are coreckt
on this website: http://sndeep.info/en
Check when your iPhone was activated on this Apple web services:
https://selfsolve.apple.com/agreementWarrantyDynamic.do
