IMessage use without service but with Wifi?

I sent my old iPhone 4S to my friend. At the moment it does not have service but he is connected to wifi.iMessage is not working and hoping anyone knows why. I used iMessage before when I had no service on the phone with wifi. I reset the phone before I sent it to him. Is there something in settings he needs to do for it to work? Thanks in advance.

Tell him to go to settings, scroll down to messages then makes sure iMessage is on.

If that doesn't work, on the same page that you can turn iMessage on and off, there's something abit below it that says send recipient, he might need to add his email there.

Since you use to use that phone, your send recipient was your cellphone number, but since it is disconnected it no longer can be used on another phone. Hope that helped:)

It will work once it sets it up on the phone, imessage and facetime can both be used free over wifi or even internationally.