Rogers Communications says a software problem was responsible for knocking out part of the company's wireless network for several hours on Wednesday evening.
Chief technology officer Bob Berner said the problem affected network equipment and caused service interruptions for voice and text messaging services across the country.
Customers of Rogers Wireless experienced widespread, hours-long outages of their voice cellphone service Wednesday evening, with the company saying it had fixed the problem by late night.
The countrywide problems also plagued Rogers's Fido and Chatr wireless brands.
In a statement on the company's website, Rogers president and CEO Nadir Mohamed says he recognizes the outage was "unacceptable" for customers.
He said technicians worked as quickly as possible to restore service and sincerely apologizes for this "significant inconvenience."
Rogers has not yet determined what caused the problem, which produced a torrent of negative customer reaction on social media networks.
"We're continuing to investigate the root cause of the issue to help ensure it doesn't happen again," said Mohamed.
"To thank our customers for their patience, Rogers and Fido will proactively credit all of its postpaid wireless customers for one day of service."
Rogers, which has about 10 million wireless customers across Canada, 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 were across Canada.
Posters on Twitter from Halifax to Vancouver said they had no voice service, and many also reported issues with text messages, or SMS.
At about 11:45 p.m., Rogers tweeted that "Wireless voice and SMS services are fully restored. We continue to investigate the root cause."
The company advised anyone with continuing difficulties to turn their phone off and on again.
1/2 Wireless voice and SMS services are fully restored. We continue to investigate the root cause. We apologize to our customers and thank— RogersHelps (@RogersHelps) October 10, 2013
2/2 them for their patience. We recommend customers power their devices off and on again should they continue to experience difficulties.— RogersHelps (@RogersHelps) October 10, 2013
Data services such as mobile apps and web browsing appeared not to be affected by the disruptions.
The main Rogers.com website was also down at around 7 o'clock and was still not loading at 8:30 p.m. It was working by 11:30.
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 had an emergency and had to call 911.
The City of Calgary advised Rogers and Fido customers who needed to reach emergency services that if they didn't have a land line, they should ask to use the phone of a neighbour or a store in their area.
With files from The Canadian Press