Pearl Flip is first BlackBerry that folds up

Research in Motion Ltd., the maker of BlackBerry phones, is set to reveal Wednesday a phone that folds in half, a departure from the slab-like design that has defined its products.

The long-rumored phone will be called the BlackBerry Pearl Flip, and will be available from T-Mobile USA and with overseas carriers later this year, at an undisclosed price.

The "flip" or "clamshell" design, where the display and keyboard are separated by a hinge, is a popular one for conventional cell phones, particularly in the U.S. Jim Balsillie, co-chief executive of RIM, said 70 percent of handsets in the country have this …