The insanely popular messaging service that still hasn’t unveiled a business model has now yanked the critical SMS part of its offering from another country, complaining of “out-of-control Canadian SMS costs”. Twitter stopped out-bound SMS to the UK, Australia and elsewhere outside the US back in August after finding SMS termination rates not to its liking. Founder Biz Stone wrote last night he was “surprised” by Canadian charges: “Please understand that we did not mean to pull the rug out from under you. We would have preferred to take more time communicating this change but we had to act quickly and responsibly.” As it grows, Twitter seems unwilling to spend cash on those fundamental SMS charges, despite raising a total $20 million so far. Stone conceded: “It’s clear we have work to do on our SMS offerings.”