How do I use iMessage when my number is disconnected?

Recently canceled cell service for iPhone 3GS (iOS 6) but have still been using it to iMessage. Today I got a message from someone I didn't know apparently AT&T reassigned my phone number to someone else and both my phone and hers were receiving the messages. How do I have others iMessage me to my email address instead of phone number?

Solution 1:

Go to the deregister page at:

• https://support.apple.com/en-us/HT203042

You can also change the send as "caller ID" portion for sending new messages in the Settings App -> Messages -> Send & Receive -> Start new conversations from:

You might have some old conversations that end since you are now using your email for iMessage so send a new message to your friends if they won't know to try your email instead of your SMS going forward.