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The White House is testing smartphones from Samsung and LG for internal use, a person familiar with the matter said, threatening one of the last and most high-profile strongholds of BlackBerry.

The devices are being tested by the White House's internal technology team and the White House Communications Agency, a military unit in charge of President Barack Obama's communications, the person said. The tests are in the early stages, the person said, and any implementation of Samsung or LG phones is still "months away." There was no indication that Mr. Obama is switching from his modified BlackBerry.

"We can confirm that the White House Communications Agency, consistent with the rest of the Department of Defense, is piloting and using a variety of mobile devices," a Defense Department spokesman said. He declined to comment on the devices in the pilot test or in use at the White House.

A Samsung spokesman declined to comment on whether its phones were being tested at the White House. "We have seen strong interest from the government sector and are working closely with various agencies to deploy pilot programs," he said. An LG spokesman said the company wasn't aware of such testing.

"For more than a decade, BlackBerry has been securing the U.S. government's mobile communications and only BlackBerry is designed to meet the high-security needs of U.S. and allied government agencies," a BlackBerry spokeswoman said.

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Obama has said he uses an Apple iPad for reading. Apple's iPhone isn't part of the testing program, the person familiar with the matter said.

Read more on the White House tech plans at The Wall Street Journal.