UPDATE 1-RIM, Apple phone 'duopoly' faces pressure -Rogers

* Slideout keyboards hitting RIM, Apple: Rogers exec

* BlackBerry, iPhone also challenged by Google's Android (Adds details, quotes, background)

TORONTO, Sept 15 - Research In Motion and Apple Inc's "duopoly" in the smartphone market will be pressured by other handset makers eager to capture increased share, the head of Canada's biggest wireless company said on Tuesday.

Rob Bruce, the president of Rogers Communications' wireless business, said he expects that phones with full slideout keyboards, as well as those based on Google's Android operating system, will chip away at the dominance of RIM's BlackBerry and Apple's iPhone.

Speaking at an investor conference, Bruce said the so-called QWERTY slider devices made by manufacturers such as Samsung <006400.KS> and LG Electronics <066570.KS> "are peeling off the low end of the smartphone market right now and in effect putting pressure on that duopoly."

He characterized Android-based phones that are making their way to store shelves as the "other major vector" in challenging RIM and Apple for dominance of the lucrative smartphone market.

'Smartphone' is a blanket term for feature-rich mobile phones that allow for more than just voice calling and text messaging. The phones offer services such as wireless e-mail and web browsing, and usually come complete with photo and video cameras and editing software.

Once the plaything and the workhorse of the professional and the wealthy, smartphones have been rapidly gaining acceptance among more mainsteam users.

The boom in adoption has meant billions of dollars in profits for their makers and also for wireless carriers like Rogers in recent years.