After upgrading my iPhone 4 to iOS5, people who were previously able to Facetime with me weren’t able contact me any longer. The calls just failed.
Turns out there was a change on my side of things that I wasn’t aware of. If people can’t reach you on Facetime, make sure that Facetime is turned on in your Settings on your iPhone/iPod/iPad.
Go to Settings > Facetime and check to make sure that you have the Facetime setting set to ON if you’re having a similar problem. Hopefully this will help someone else out!