No, I didn't consciously do anything to the software. I've only had the phone for a few months, and I've never done anything to the software. Now it's impossible to place a call, although it will still receive a call.
Yes, the factory reset did solve the problem, but it is not much of a solution because android is too dumb to segregate ones data from its executable code. The result is that the data is deleted as well as the code and one is left with a fairly useless toy that is no match for an old style cell phone.