Can I unblock a Sprint iPhone 4s and use in an international carrier?

Since the phone doesn't have a SIM card slot, am I still able to use it? Also I can't find the IMEI of it, I went to Setting > About & it's not showing…

If there's no SIM card slot, then it's not a 4s. It's a 4. That should be stated under Settings > About too. 4s is a dual band mode for CDMA and GSM. Unlocked it would work but if there's no slot then it's CDMA only and can't be used overseas since most everywhere else on earth uses GSM. Best luck.