BlackBerry (BBRY) is at the start of a very long haul as the struggling smartphone maker attempts to stage a comeback for the ages. Early sales of the company’s first next-generation BlackBerry 10 smartphone appeared strong, but a series of subsequent claims suggested limited supply was responsible for many of the BlackBerry Z10 stock-outs being reported in the United Kingdom and Canada. We now know Z10 sales to date are likely nothing to scoff at, however — BlackBerry’s Z10 is outselling the iPhone 5 and the Galaxy S III at a major Canadian retailer — and BGR has confirmed an even more important indicator of BlackBerry’s early success: Half of BlackBerry Z10 sales in Canada and one-third of UK sales have been made to users coming from other platforms.

CIBC analyst Todd Coupland reported last month that 50% of pre-registration for the Z10 in Canada came from users who did not already own BlackBerry devices. Interest doesn’t always translate to sales though, and it was unclear if BlackBerry would be able to get these iPhone and Android users to commit to the Z10 following its release.

BGR has now learned from multiple trusted sources that BlackBerry has indeed managed to pull off the coup it so desperately needed. Several high-level BlackBerry executives have confirmed internally that half of all BlackBerry Z10 sales in Canada have been made to new customers coming from other platforms.

What’s more, one-third of Z10 sales in the UK, another key market for BlackBerry, have been made to customers who did not already own BlackBerry smartphones.

BlackBerry declined to comment.

Early reviewers — including us here at BGR — worried that while BlackBerry 10 showed great promise and the Z10 was a terrific early effort, the new operating system didn’t offer any compelling differentiation that might draw users away from the iPhone and Android smartphones. If early performance in these two key markets is any indication, however, BlackBerry’s new platform may be a bigger draw than we expected.