CALGARY -- With robberies at retail cell phone stores increasing in recent years, police in Calgary and Edmonton are teaming up to protect consumers.

Around 600 phones have been reported stolen over the last two years, including 25 robberies this year in the province's two largest cities.

"Stolen cell phones are later resold online or in-person to unsuspecting buyers who are not aware they are purchasing a stolen device," Calgary police said in a release.

"Worse yet, buyers may end up purchasing a stolen cell phone that has had its International Mobile Equipment Identity (IMEI) number registered on the national blacklist, thereby rendering the device unusable."

Cell phones have an unique IMEI number that can be found either in the settings menu of the phone, on the back of the device, underneath the battery or inscribed on the SIM card tray.

To increase awareness, Calgary and Edmonton police are partering with TELUS, Bell, Rogers, and Shaw Communications, along with EBay and Kijiji.

"The campaign aims to reduce the frequency of cell phone theft and robberies, as well as help prevent unsuspecting buyers from purchasing a stolen and inoperative phone," police said.

The campaign will features ads on eBay and Kijiji, directing cell phone buyers to the Device Check Canada website, operated by the Canadian Wireless Telecommunications Association (CWTA).

 "Consumers can visit the Device Check website to see if the IMEI number of the phone they are interested in purchasing has been entered into the national database, thereby indicating that the phone has been reported stolen and is unusable," police said.

"The IMEI number of a stolen device can only be added to the national database by wireless service providers, so it is crucial for victims of cell phone theft to alert their service providers immediately."

When buying a used phone or one from the secondary market, consumers should ask the seller for the IMEI number beforehand and use the Device Check website.

If the IMEI number is not listed, buyers should consider waiting a few days before checking it again in case the phone is stolen and hasn't yet been reported.

"This collaborative initiative is meant to be a preventative measure by providing buyers with an additional step in hopes of engaging in a safe and secure transaction," said Det. Stephen Horton of the CPS robbery unit.