An Optus store at Gungahlin had its front windows smashed in a robbery on Thursday morning, one of three stores broken into across Canberra overnight.
The Curtin Newsagency and a Telstra store in Fyshwick were also broken into, according to police.
Police did not initially believe the incidents are linked but investigations are ongoing.
Police said display phones were likely to have been stolen from the Optus store on Hibberson Street, which was broken into at about 4am on Thursday.
The offenders gained access to the store by smashing the front window.
Security guards contacted police when the alarm sounded.
Police said it was also likely display phones and tablets were stolen from the Telstra store in Fyshwick and offenders also broke in by smashing the front door, at about 2.30am.
The Curtin Newsagency break-in happened at 3am.
Police said they would review CCTV footage at all locations in the hope of identifying offenders.