How to unlock my iphone 4 and 4s for free?

Want to unlock my iphone 4 and 4s.

According to my experience, There's no free unlocking service for your iphones.
So you have to go for paid service. You can get an unlocking service from your service provider or else try to get an unlocking service from any one of the online unlocking service provider like http://www.theunlockspot.com/apple/rs10wp8/ Here you can unlock your iPhone using Remote unlocking method. It's one of the best and safe way to unlock your iPhone without jailbreaking.