So after my odd error with the phone receiving calls, but not answering/dialing them, I decided to restore the phone ("un-jailbreaking" it) and put my last backup into it.
I tried calling my home number, and still the same error is returned: "Call Failed." I receive calls, but when I dial a number (or pickup a call), the error is returned. My data connection is working fine.
Can someone please give me a hand here... I jailbroke with QuickPwn 2.2.5 and I have iPhone 3G SW 2.2.1 loaded, with the new carrier settings installed.