Rogers Wireless says customers may experience intermittent issues making or receiving wireless voice calls.
In a message posted Monday on its website, the company said it was experiencing an outage that was affecting many wireless customers.
The message said "some customers may be intermittently experiencing dropped calls or are unable to place or receive calls on their mobile phone or wireless home phone service."
Late Sunday night Rogers announced that its network teams were working to resolve the issue as quickly as possible, however, it didn't say when it expected the problem to be fixed.
Telus says some of its customers may have issues calling customers on other networks, but calls to other Telus customers and Bell customers are unaffected.
It says it is continuing to monitor the issue as the providers work to resolve their outage.
With files from the Canadian Press