We were in Nevada, California and Arizona in Oct 2016 and only got service when there where AT&T towers. There were many areas that AT&T didn't cover like around Calaveras County CA, Cave Creek AZ, and outside Flagstaff AZ. People from the US we were with did get good coverage from other providers. Does Koodo only have an arrangement with AT&T? We felt like we wasted our money buying the roaming add-on when it doesn't work 25% of the time.