Sony Ericsson's as yet unannounced W999 Walkman slider phone has appeared on the web in an official capacity, turning up among the GSM Association's list of HSDPA-compatible handsets.

Sony Ericsson's W999 (left) appearing on the GSMA website

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The site also mentions the Z750, an HSDPA-enabled clamshell handset Sony Ericssion when public on back in March this year.

The GSMA provides no information about the W999, but it does show what it looks like. The image confirms past claims that the W999 sports a QWERTY keyboard with two characters per key rather like the one on Sony Ericsson's M600 smart phone. Its colour scheme suggests an aboreal inspiration of the kind behind the recently announced S500.

The W999 is also believed to feature a 2.4in, 240 x 320 display, and to be 1.3cm thick.