Rogers Communications customers using wireless voice and data services have faced intermittent interruptions for several hours.
The Canadian cellular and cable operator said in response to complaints on social media on Monday that residential and business wireline internet services were not impacted.
Around 11,000 users reported issues with the wireless service provider as of 1900 GMT, according to outage monitoring website Downdetector.ca.
Downdetector tracks outages by collating status reports from a series of sources, including user-submitted errors on its platform.