Calgary police are warning consumers to keep their eyes peeled when perusing online marketplaces and classified websites after a rash of recent cell phone thefts from local retailers."We do have ongoing robberies for retail cell phone stores or electronic stores where offenders are then stealing these phones and then reselling them to victimized people through the online marketplace," said Staff Sgt. Mark England with Calgary police.Such thefts have taken their toll on Geoff D'arcy, who has run a cell phone repair business for more than a decade. In the past four years, his shop has been broken into four times."The first time it was a lot of customer devices, which was unfortunate. But future times it's always been our pre-owned phones," D'arcy said.Efforts to inform the public about stolen phones are important, D'arcy said, but "long overdue.""I think it's really important. I think a lot of people do get caught buying stolen phones," he said. "We have people in here, probably daily, that have bought a cheap phone online and it turns out it's stolen, so it can't be activated."Cell phone thefts can often be sudden, like in September of last year when a group of men in sunglasses and hooded sweatshirts stole dozens of iPhones from the Apple Store in Calgary's Chinook Centre.Police are urging the public to ask for the serial number or International Mobile Equipment Identity (IMEI) number. Each smartphone comes equipped with a unique number which allows stolen phones to be identified.Buyers can check the IMEI number online beforehand, which will reveal whether the phone has been reported stolen or is blacklisted."It's not something that most people are aware of," England said. "Those are hugely important, investigatively, for us to be able to track the phone."