I have A T & T and their service in Boulder, CO isn't good due to the mountains. that's what they told me anyway. more towers!! I had to go outside the hospital to make a call while everyone else was able to use their phones inside. also in hospital on other side of Boulder, my phone worked inside for calls to outside but I never got calls from relatives calling me. odd. phone never rang and it was on. sigh. so maybe a change would be good.