I currently live in the US and I just recieved a replacement iPhone for one with a faulty screen and the new one has trouble connecting to 3G networks in areas where there is for sure 3G data. I can connect by turning 3G off then on, so obviously there is coverage, and I was wondering if turning data roaming on will either 1) make my phone connect to 3G networks automatically and 2) make my bill more expensive or 3) if this is a problem that would require me to get another replacement. Thanks.