I have been very impressed with T-Mobile service over the last couple of years. HOWEVER, I have been spending time in Co. Springs and Denver, CO and I have to say their service leaves a lot to be desired. Downtown Co. Springs you can't even get data service and I am finding similar gaps in areas of Denver that I almost never experience in other areas of the US. Not sure what caused these CO issues but I am really happy I have AT&T data service in the RV.