Coverage is function of location and number of cell sites. A single CDMA site has a larger coverage area than a GSM site. Tall buildings can reflect cell signals and cause dead spots which can be fixed by adding more cell sites. Coverage maps may be more based on theory than measurement. When you get out into nature you will loose cell coverage. If you were stateside I'd recommend Verizon which is CDMA. Verizon includes the old GTE Mobilenet. Finding friends with different carriers and comparing the number of bars may help you make the best decision for you.