For cell/wifi service in rural USA, there's 2 things to consider. One is the signal grabbing capability of your phone. All phones are not created equal. Some phones will actually lose the signal by the way you hold the phone in your hand. Two, see if you have a CDMA phone or a GSM phone. CDMA has an extremely better footprint over the US map, especially the mountain and west coast States. However, and interesting to note, is that the list of the major 125 carriers in the USA is split 40% CDMA and 60% GSM. Verizon (for one), uses CDMA, while AT&T & T-Mobile (among others) uses GSM. If have AT&T, and your from the East visiting the West Coast, expect to have lots of dead zones in the canyons and valleys, even those in the cities. However, those with CDMA phones will not be able to reach out and touch someone while visiting Asia and Europe.