How can I add a phone number to be reached at on FaceTime/iMessage?

[iMore Question]

I recently got an iPad from att and it has 4G and has it's own phone number. But the problem is... I cannot add the phone number to be reached. It only allows me to be reached at my email. I have read many forums and even gone to multiple att stores but no one can seem to help. I don't want to pay for data usage for nothing if it only allows the email and not a phone number (yet it has its own number)

 

[anon(9208252)]

It works via email, or people with iPhones, if you have an iPhone make sure it is turned on, it should show automatically .