NEW YORK (Reuters) - AT&T Inc , the biggest U.S. mobile service, said on Monday it will sell a new handset from Pantech Co aimed at customers who like to send e-mails or text messages.

AT&T is bolstering its phone line-up for the holiday season with the Pantech "duo," which runs on Microsoft Corp's mobile phone operating system and has a miniature computer-like keyboard, as well as a standard phone keypad.

Unlike Apple Inc's iPhone, the Pantech duo runs on AT&T's high-speed wireless network. It will go on sale on Monday and will cost $199.99 for customers who sign on for a 2-year contract.

The phone will likely compete with Research in Motion's Blackberry devices.

The matte grey phone has a relatively big screen for Web surfing and a standard phone keypad that slides out from under the bottom of the phone and a so-called "QWERTY" keypad that slides out from under the side of the phone for emailing.

South Korea's Pantech had its shares delisted in April as the company under-went a credit-led restructuring.

It trails bigger Korean rivals Samsung Electronics and LG Electronics Inc and has suffered from stiff competition from cell phone market leader Nokia Oyj.
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