Just because your cellphone works at home doesn't mean it'll work deep in the woods of northern Maine -- or even at that rustic country B&B, thanks to our nation's (and the region's) fragmented and competing cellphone coverage systems. You may or may not be within your roaming area, even if you have a national calling plan. It's a good bet that your phone will work in the region's major cities, so look over your wireless company's coverage map on its website before heading out to be sure; T-Mobile, Sprint, and Nextel are particularly weak at covering rural areas.
If you need to stay in touch at a destination where you know your phone won't work, rent a phone that will from InTouch USA (tel. 800/872-7626; www.intouchglobal.com) or from some rental car desks; just be aware that you'll pay $1 a minute or more for airtime anytime you use the phone.
If you're not from the U.S., you'll be appalled at the poor reach of the GSM wireless network (which is used by much of the rest of the world) here. Your phone will probably work in most cities and interstate corridors in northern New England, and along much of the southern Maine coast; but it definitely won't work in most of the rural areas, which means nearly all the rest of the region. You also may or may not be able to use SMS (in other words, send text messages) home.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.