Phonewords on a Blackberry...?

Pop quiz, techies: how do you dial phonewords (of the format "1-800-LETTERS") on a Blackberry keyboard like the one in the photo? It's a problem deftly identified by fellow usability blogger Jasper of Uselog a few months back. Remarkably, it turns out that Blackberry provides a solution: Geekberry points out that you simply press "shift" and then spell out the word - the Blackberry will do the conversion and dial the right number itself. Of course, that trick isn't exactly obvious - it definitely requires you to RTFM. Usable enough? Doubtful - it will completely evade anyone who's not in the know, and even those who read about it may dial phonewords so infrequently that they'll forget the trick in between uses. Advantage, iPhone...