New phone on it's way
I too had been having the 3G connection issues that are the same as the other's who posted here. After two very long tedious calls to Sprint CS; and after doing all of the stuff they have you do (up to and short of a factory reset) and ending up not being abel to get ANY signal with a Mobile Network status of "Disconnected" for two days, I went to my local Sprint Store that has a repair center. They tried a bunch of stuff; did a factory reset, the tech in the repair center back room hooked it up to whatever they hook it up to, and the CS person came out and ordered me a new phone. It'll be at my house in two days. I tried to get what was wrong with my phone out of the guy but he would only say that it was being replaced.
I sort of felt all along it was the phone; the Sprint support people on the phone were all over the "it's the towers" deal but I was just not buying it. I live in a Columbus, OH suburb very close to the Sprint store I visited. One of the first things I asked is if there were a lot of people coming in complaining about 3G signal issues. A big "nope" to that. It's got to be something wrong with the radio in the phone. Anyway, my fingers are crossed that the replacement, which I was told would be a new, not refurbished one, works as expected.