The latest satellite phones and SOS beacons keep you in touch, even at the ends of the earth. Douglas Dixon reports

When Jacki Wilbur joined the Peace Corps in 2005, after graduating from college, she volunteered to serve in a remote village in Ghana where the only phone was in the church—and was rarely answered. "We were faced with the fear of being out of contact with our daughter," says her father, Curt Wilbur. So the Wilburs bought a satellite phone (which they had learned about on an earlier trip to Alaska's Glacier Bay), then Curt flew to Ghana and delivered it to their daughter. "The phone helped Jacki stay connected with us and with the other volunteers. We also could send text messages, which were free," Curt says. "It gave us a great deal of reassurance and comfort."

Until a decade ago, satellite phones were the size and heft of a suitcase, and only professionals—scientists stationed at far-flung outposts, adventure outfitters—bothered lugging them around. In 1998, Iridium introduced the first handheld satellite device, a nearly one-pound phone with a $3,000 price tag and $7-per-minute airtime charges. Today's models are smaller and cheaper: Most cost less than $1,300, and calling plans can dip under $1 a minute. Sound quality is also improving, although the phones work best beneath an unobstructed sky—in the African savanna, say, or on the open sea. Coverage also depends on which satellites the phones use. Globalstar, a leading manufacturer, offers some of the widest coverage and some of the smallest phones on the market, but until it launches new satellites in 2010, service will remain spotty. Here's a closer look at the two most popular brands.

THURAYA

These compact phones have built-in GPS and color displays. The SO-2510 is satellite-only; the SG-2520 is also a GSM mobile phone.

Where they work: In Europe, the Middle East, Australia, central and southern Asia, and most of Africa.
Our test: The SO-2510 found the network in two minutes in the Jordanian desert. The first call, to Syria, was clear, with no feedback or delays. The second call, to the United States, was dropped—perhaps due to severe weather.
Specs: The SO-2510 weighs 4.6 ounces, the SG-2520 6 ounces; each has 2.4 hours of talk time, 40 hours of standby time.
Pros: Small and light. Photos and text mes-sages upload quickly.
Cons: No coverage in the Americas or near the North and South Poles.
Cost: SO-2510, $675; SG-2520, $1,275 (explorersatellite.com).

IRIDIUM

The 9505A is a satellite phone. Iridium has the largest network of satellites (66) and subscribers (more than 180,000).

Where it works: In every country except North Korea; also works well on the oceans and near the North and South Poles. Best used in an open area with unrestricted sky views.
Our test: In Bhutan, reception was best outdoors and at high altitudes. In valleys, the voice on the other end sounded squeaky and calls were often dropped.
Specs: The 9505A weighs 13 ounces; it has 3.2 hours of talk time, 30 hours of standby time.
Pros: Works around the globe. Water-, shock-, and dust-resistant.
Cons: Bulky, with an 8-inch antenna. Calls can cut off after 5 or 10 minutes when the phone is not used in an open area. Photos and text messages upload very slowly.
Cost: $1,395 (explorersatellite.com).