Customers of Rogers Wireless are experiencing widespread outages of the company's voice cellphone service, with no indications of when the disruption will be fixed.
The countrywide problems are also plaguing Rogers's Fido and Chatr wireless brands.
The company first confirmed on its Twitter feed at 6:40 p.m. ET that it was experiencing "voice service interruptions affecting wireless customers in Ontario & Quebec," but later updated to say the outages are across Canada.
Posters on Twitter from Halifax to Vancouver say they have no voice service, and many are also reporting issues with text messages, or SMS.
An email to CBC News from a Rogers spokeswoman said the company doesn't yet know when service will be restored.
"We don't yet have an estimate on when it will be resolved, but we're working to restore service as quickly as possible," wrote Jennifer Kett, senior manager of media relations.
Data services such as mobile apps and web browsing appeared to be operating.
The main Rogers.com website was also down at around 7:05 p.m. ETand was still not loading at 8:30 p.m.
The Rogers toll-free help line said the company was experiencing unusually high call volumes.
Police in Toronto warned residents about the problems in case they have an emergency and have to call 911.
The City of Calgary advised Rogers and Fido customers who need to reach emergency services that if they don't have a land line, they should ask to use the phone of a neighbour or a store in their area.