Cingular’s 8525 (HTC TyTn) has that vestigial, and now useless, push-to-talk button. It was marketed as having the feature, but having the feature is a completely different story from actually enabling the feature. An anonymous tipster over at Engadget Mobile says they got the down-low on the promised PTT-enabling firmware update come April 25 – with some bug fixes thrown in for good measure. We’re hoping the tipster is right about the firmware upgrade, because that would make the source’s prediction of a Windows Mobile 6.0 arrival in Q3 2007 that much more credible.