Can iPhone 4S without plan use message?

I use an old iPhone 4S like an iPod until I get my plan set up. Since iMessage uses email I thought I could still use it without a number. Not workin. Don't say I'm stupid or use any dumb remarks just give me an answer. Thanks
Plus, since iPods use iMessage shouldn't it work for me if I set it up like the iPod?

Yes iMessage with Wi-Fi only.

Yes it should work just like an ipod touch if you are connected to Wi-Fi. Don't know what you are doing wrong

Yes, you can use the iMessage but you need to have internet, you can use Wi-Fi to send iMessage.