Is iPhone iMessage free without Wi-Fi?

I was wondering if there's any chance that you can iMessage other iPhone for free because I'm thinking of going on a Pay As You Go sim card but will you still have to pay without Wi-Fi?

I message is free I think

It'll use your mobile data allowance

Yes. But get a unlocked iphone and use simple mobile or h2O and the are 40.00 flat and 50.00 flat unlimited a month

IMessage is free as in you don't have to pay extra for the service on top of what you already pay the Carrier. So yes, iMessage will still be "free"

Let me clarify.iMessage is a data that uses your network connection to send messages and your traditional means of SMS. It 'will' use your phones data if not hooked up to a local Wi-Fi. The person receiving will also use data to retrieve the messasge if not hooked up to Wi-Fi. If both of you have data off and don't have local Wi-Fi then iMessage won't work.

Yes. If you aren't using Wi-Fi you are using 3G where there's a charge.