We use a hot spot with AT&T service. In 2013 had 3G and 4G service in the following locations:
3G - Tok
3G - Pull out at MP 174.8 on the Glenn Hwy
4G - Palmer
4G - Eagle River
4G - Anchorage
4G - Wasilla
3G - Willow
4G - Talkeetna
4G - Healy
4G - Fairbanks
4G - North Pole
4G - Valdez
Most of the places we stayed had internet but ours was better. Some charged, some were free, and some were very slow.
We never used it going through Canada because there is an International roaming charge. Used the internet at the campgrounds.