Why wont my iMessage work on my iPhone?

I was wondering why my iMessage service does not work on my 3GS phone. The iMessage tab is switched to on. The recipient and I are both within wifi connectivity. The send button even turns blue. When I try and send MSG it says not delivered. When I gO to settings and turn imsg tab off then bk on, it says waiting for activation… How do I activate for starters?! I have put my password and used ID in too but still to no avail! What do I do? Thanks

IOS6: Messages (iMessage) not working, How to fix - Apple Toolbox
appletoolbox.com/… /ios6-messages-ime…
30 Sep 2012 - Several users have reported that iMessage has stopped working, meaning they are unable to send or receive messages after they upgraded…

Click on the link it details how to get around the problem you are having. Hope this helps you out a little

Sign in and wait, when it takes you into the IMESSAGE app then you should be good.

I have the same problem.

When I try to sign in to turn on my iMessage it kicks me out and won't turn it on. What do I do?