Danish telecoms operator TDC Net has suffered a major telecoms outage.

The telco, which is Denmark's largest network provider, blamed the outage on a software update it implemented on Wednesday, November 27.

The outage has meant thousands of customers have been unable to make phone calls, including making calls to emergency services at 112.

ABC News reported that the telco doesn't believe the outage has been caused by a cyber attack.

The publication also reported that the outage meant that at least one hospital was forced to reduce non-critical medical care, and prompted security services in some regions to patrol the streets in search of people in need of help.

TDC Net said it had implemented a fix to allow customers to make calls, although with a reportedly reduced sound quality.

The carrier has told customers to remove their SIM card before calling 112.

TDC Net provides mobile, fiber, and copper services. TDC Net was created in 2019 by TDC Group, which split its mobile and broadband assets from its TV offering, the latter of which sits under its Nuuday brand.

The company can trace its roots back to 1879, when Alexander Graham Bell's Bell Telephone Co. opened its branch in Denmark. Two years later, in 1881, the company opened the first telephone exchange in Copenhagen to serve the city’s 22 subscribers.

Update: TDC Net confirmed a day later that a technical error in its Ericsson core network was to blame for the outage.

"Yesterday, our network was challenged by a rare major operational disruption, which meant that we were unable to deliver the service that our customers are used to getting from us. As the chief executive of TDC Net, I would like to offer an unreserved apology to everyone who was affected. We know that this put many customers in a difficult situation - and worst of all those who tried in vain to get through to the emergency center. We should - and we will - do better in the future," said Michel Jumeau, CEO of TDC Net.

Ericsson also put out a statement, shouldering some of the blame for the disruption.

"Ericsson regrets the incident on Thursday in Denmark, which affected TDC Net's mobile network. We are now working hard with our customer to identify the cause and will do our utmost to prevent it from happening again," said Ericsson.