Most phones, including the iPhone, get only spotty service in the Colorado mountains. Service at Breckenridge is OK. My iPhone gets service at the top of Vail, and at some places on the front side, but that's about it; nothing in the back. Keystone gets spotty service on the frontside, but nothing beyond that. A-Basin is total nada. The best use for my iPhone in the mountains is as an iPod.