But will your iPhone work in the desert?

Now that it's officially summer, Californians are running for the hills, mountains, deserts and oceans for a little bit of vacation time. But if you're one of those people for whom vacation means obsessively checking your Gmail on your BlackBerry five times a day (and if you're reading this blog, we're guessing you are), the time away can be maddening. That cottage in the mountains is charming enough until Day 3 without cellphone reception.

Wireless coverage is spotty in most of California's national parks, where it might be hard to enjoy the waterfalls and mountains if you're going through Internet withdrawal. Worse, not everyone is similarly afflicted. Climb Yosemite's Half Dome and pull out your BlackBerry to call your mom, and your phone might not work, while the hipster in hiking boots next to you is chatting happily on his iPhone.

So we did some homework for those of you considering heading into some of California's most popular remote destinations this summer. Knowing which cellphones get coverage could be very helpful when you're lost or wondering if you really can eat those berries. We looked at coverage in Joshua Tree, Death Valley, King's Canyon, Sequoia and Yosemite by comparing the coverage maps of the big four cell providers with the maps of the park's boundaries. Our conclusion is that if you're buying a mobile phone just for the reception in the wilderness, go for Verizon Wireless and stay away from T-Mobile. Although your best bet ...

... is probably to get a homing pigeon.

In Yosemite National Park, where intrepid hikers can gaze at waterfalls and climb large blocks of granite, T-Mobile's map shows that it has no reception anywhere, not even once you leave the park and are merely in the boonies. Verizon's map shows it has roaming coverage in Yosemite Valley, as do AT&T and Sprint.

Moving south to King's Canyon and Sequoia, where tree huggers can hug really, really big trees and climb the Sierra, AT&T, T-Mobile and Sprint all lack reception. Verizon's helpful map, which has shaded green areas to tell you where the national parks are, shows that customers will have coverage in the southwest parts.

Death Valley, just east of King's Canyon, isn't a place many sane people would head to in the summer, even though the sand dunes and mountains are pretty amazing. But if you are going, don't depend on your cellphone when your car breaks down in the middle of the desert because you had the air conditioning jacked too high. None of the wireless providers offers much reception to speak of. Sprint's map shows a bit of roaming in the west part of the park, although the map is a bit difficult to read (it doesn't show many towns to use as reference points).

Finally, there's Joshua Tree, the park of choice for SoCal rock climbers and cactus lovers. This is your best bet out of all four parks for getting cell service on a hike. AT&T, Sprint and Verizon all show moderate service, mostly in the northwest corner near Twentynine Palms, while T-Mobile's coverage is in the east end of the park.

Why such discrepancies? It's all about a company's infrastructure and shared networks. Verizon, for instance, had worked out roaming agreements with smaller carriers, operating its service on their networks and charging customers a roaming fee. That's why Verizon customers in Yosemite get some service, while T-Mobile customers don't.

A T-Mobile spokesman said the company hadn't gotten many requests for service in remote parks like Yosemite and Death Valley, and that T-Mobile prefers to set up its own cell sites rather than negotiate roaming agreements, which can prove quite costly. That will change if T-Mobile customers start to request coverage in the parks.

You could argue, of course, that it's all for the best, and that people hungering for cell reception even in the wilderness deserve to go through some withdrawal. But most customers don't see it that way. Especially those with vacation homes in the boonies.

"If someone takes a vacation in the same spot every year, we hear about it," Verizon spokesman Ken Muche said. "They'll say, 'You have coverage in Yosemite and so-and-so doesn't and we're really grateful for it.' "

Do you have any good tips on using your cellphones in national parks? Or funny stories about times you really could have used phone access but couldn't get it? We'd love to hear from you in the comments below.

-- Alana Semuels

Semuels, a Times staff writer, covers marketing and the L.A. tech scene.

Photo: Snapping a photo of Yosemite Falls on a cellphone. Credit: Robert Durell / Los Angeles Times

Comments

[Rick Deutsch]

A timely article. I've hiked Yosemite's Half Dome 22 times and witness the frustration of friends trying to use their phone. My ATT reception is spotty in the Valley, but does get bars in Curry Village and the main parts of the Valley. Nil on the actual hike (due to mountian blockage). Most people do get reception when standing on the summit of Half Dome (8842'). Calling mom to say "guess where I am."

Rick D
San Jose
www.hikehalfdome.com