In the rest of the country, people hate on BlackBerrys. Chaos — and lawsuits — ensued after a major service outage last month. According to a report released this month by Nielsen, BlackBerry-maker Research in Motion’s U.S. market share has slipped to 18 percent, down from 30 percent at the same time last year.

But not on the Hill. Here, almost everybody uses BlackBerrys, even though Senate staffers can choose between BlackBerrys and Apple iPhones, and House staffers can choose among BlackBerrys, iPhones and Google’s Android devices.

According to the Office of the Chief Administrative Officer, there are about 10,600 government-supplied smartphones being used by House staffers. Of those, about 1,500 are iPhones and 100 are Androids. The rest — about 9,000 — are BlackBerrys.

Although the Senate Sergeant-at-Arms’ office could not supply exact numbers for that side of the Capitol, a spokesman confirmed that BlackBerrys far outnumber iPhones.

One possible explanation for the preference is institutional inertia, or “a ‘not broke, don’t fix it’ mentality,” explained Ken Yarmosh, founder of Washington, D.C.-based mobile agency “savvy apps.”

“When it comes to technology, people are creatures of habit,” Yarmosh said in an email. “On Capitol Hill, that’s even more true.”

Yarmosh also attributed the lasting power of BlackBerry to its keyboards, explaining that the people making equipment decisions “are scared of iPhones and other smart phones that don’t have physical keyboards.”

Scott Rodman, director of information technology for Senate Majority Leader Harry Reid (D-Nev.), agreed with the keyboard argument. “Even today many staff prefer the tactile keyboard over the ‘soft’ keyboard,” he said in an email. “This is slowly changing, though.”

Rodman also pointed to price as a possible explanation for the difference in popularity among phones. “The [BlackBerrys] generally come in at a pretty hefty discount,” he said. “While those discounts don’t always apply to other devices.”

A benefit of BlackBerry devices is the BlackBerry Messenger feature, which allows communication between BlackBerry devices without using the email system. According to Rodman, this “circumvents some of the bottlenecks with email in an emergency situation where data coverage can be saturated,” such as during August’s  earthquake in Virginia.

Another explanation relates to the technical differences between the three devices. Because of differences in the setup of the phones, BlackBerrys are granted direct access to Congressional mail, while iPhones and Androids must access Congressional mail through an application made by Good Technology, which is forced to disconnect from the Internet connection when inactive on the iPhone. The same application is used by Fortune 500 companies, major financial institutions and government agencies such as the Department of Defense.

According to the “Dear Colleague” letter announcing the introduction of the iPhone to the House system, those using the Good Technology application cannot access email with the same speed as those using BlackBerrys. “The iPhone 3GS’s functionality on the House network is not the same as the Blackberry device,” said the announcement, which provides a link to a comparison chart located on the House intranet. “While users of the iPhone device will be able to access their House email accounts, their emails will not be received in ‘real-time’ as they are on the Blackberry,” the announcement explains.

“With BlackBerry devices, a user is notified when the email is downloaded to the device,” explained an email from Dan Weiser, communications director for the Office of the CAO for the House. “With the Good application, a user is notified that a message is ready to be downloaded. The user opens the application and the message is downloaded.”

Brad Fitch, president and CEO of the Congressional Management Foundation — a group that has received past funding from RIM — recounted hearing staffers express their displeasure with the iPhone’s time lag in receiving Congressional email: “They didn’t seem satisfied and felt that it is not meeting their needs.”

Fitch said this is an example of Congress’ constant struggle to keep up with an ever-changing technological landscape. “This is just frankly a function of the rapid growth of technology and the challenge that offices have to try to keep up with it,” he said. “The pace of tech is so fast. … It’s a real challenge for Congressional offices to adapt.”

It makes sense that people are satisfied with a professional phone for work, Fitch said, because so many have a consumer phone such as the iPhone or an Android device for their personal business.

“I am often stunned at the number of people who walk around with multiple devices,” he said. He called Congressional offices “like the Wild West of technology,” comparing the number of devices people carry on their hips to six-shooters.

According to Weiser, the Office of the CAO for the House is not opposed to opening up email access to other devices as they become relevant in the future. Right now, it’s a question of security.

“Devices are approved after they are certified to integrate with the House’s email solution and do not introduce unmitigated risk to the House environment,” Weiser said.