The company says the problems are concentrated around Calgary and Hamilton, Ont., and that while 311 service is affected, 911 service is not.
Calgary's Mayor Naheed Nenshi tweeted, "some challenges with city phone services including 311 this morning. Shaw and City IT are on it. Thanks for your patience & consider 311 app."
In an online forum about the issue, commenters from Airdrie, Cochrane, Okotoks and Edmonton said their phone lines were also down. All said there was no dial tone when they tried to use their phones.
Shaw says they don't know when service will be back up but that they are using social media to keep users informed about the problems.