Just because your cellphone works at home doesn't mean it'll work everywhere in northern New England (thanks to our nation's fragmented cellphone system). It's a good bet that your phone will work in major cities, a bad bet it will bail you out of trouble deep in the Green or White Mountains. But take a look at your wireless company's coverage map on its website before heading out -- T-Mobile, Sprint, and Nextel are particularly weak in rural areas. If you need to stay in touch at a destination where you know your phone won't work, rent a phone that does from InTouch USA (tel. 800/872-7626; www.intouchglobal.com) or a rental car location, but beware that you'll pay $1 a minute or more for airtime.
If you're venturing deep into the backcountry of northern Maine or the mountains, places where cell towers might never be built, you may want to consider renting a satellite phone (satphone), which differs from a cellphone in that it connects to satellites rather than ground-based towers. A satphone is more costly than a cellphone but works where there's no cellular signal and no towers. Unfortunately, you'll pay at least $2 per minute to use the phone, and it only works where you can see the horizon (i.e., usually not indoors). In North America, you can rent Iridium satellite phones from RoadPost (www.roadpost.com; tel. 888/290-1606 or 905/272-5665). InTouch USA offers a wider range of satphones but at higher rates. As of this writing, satphones were amazingly expensive to buy, so don't even think about it.
If you're not from the U.S., you'll be appalled at the poor reach of our GSM (Global System for Mobiles) wireless network, which is used by much of the rest of the world . Your phone will probably work in most major U.S. cities; it definitely won't work in many rural areas. (To see where GSM phones work in the U.S., check out www.t-mobile.com/coverage/national_popup.asp.) And you may or may not be able to send SMS (text messaging) home -- something Americans tend not to do anyway, for various cultural and technological reasons. (International budget travelers like to send text messages home because it's much cheaper than making international calls.) Assume nothing -- call your wireless provider and get the full scoop. In a worst-case scenario, you can always rent a phone; InTouch USA delivers to hotels.