HERE IS HOW I SOLVED THIS ISSUE:
(I just upgraded my 4s 16 GB to 4s 64GB IOS 6.1)
Before I started the upgrade I performed the remote wipe (still not sure if that has anything to do with the problem or not), however after activating the phone, both Imessage and FaceTime, would not associate with my phone number. I could add my apple ID but that was not my goal.
Immediately after the phone swaps, my phone # was showing as UNKNOWN under Settings, Phone.
To resolve this I put the phone in the Airplance moder ON/OFF and my phone number appeared.
So, my cell number was there (for both iMessage and FaceTime), however it was grayed out and I could not select it as my primary contact address (or number)
I talked to Apple and this is what we tried, without any immediate results:
1.Turn Imessage on and off
2.Turn Face Time on and off
3.Changed Time zone from auto to manual and then back to auto
4.Reset Network Settings 2x
I restored the phone 2x to factory setting, however that didn't produce any results.
Finally, I came across a post that said, TO KEEP THE iMessage and FaceTime toggle ON and let it sit that way for a long time. Apparently switching it ON/OFF looses its spot in the activation queue.
P.S. I was logged in with my apple ID on both apps, and after 3 hours today (without touching the settings) it finally registered itself. My IPad showed a banner saying that my iPhone was registered with my phone number and that's how I found out the process was done....hope this helps.