Why won't my iphone place calls anymore?

This didn't happen until I upgraded to ios 6 last night and since then I can't place a call. I will select a person to call and it starts but it never connects then just says call ended. I have an iphone 4, that i got a few months ago.

Added (1). I can still text, listen to music, surf the web, basically everything else

Added (2). I have turned it on and off, and also done a hard reset, neither worked

Contact Apple or store of purchase, or do a hard reset (Home and lock key together)

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