Denmark paralyzed: nationwide mobile network failure halts trains and emergency services

TDC, Denmark's largest telecom provider, experienced widespread service outages earlier today, leaving thousands of customers unable to make calls — including to emergency services at 112, as per a report by The Copenhagen Post.

The disruptions appear to be linked to a software update implemented Wednesday, according to TDC Communications Manager Lasse Bjerre Sørensen. While the exact cause remains under investigation, Sørensen told local broadcaster TV2 that the company is reviewing its procedures to prevent similar issues in the future.

The news emerges as concerns mount over undersea internet data cables being cut or damaged, with incidents reported in several European countries, including Germany, Finland, Sweden, and Lithuania.

“We are looking thoroughly and seriously into it, also in light of the current political situation. I note that the German and Swedish authorities are suspecting sabotage,” Danish Minister of Defense, Troels Lund Poulsen, said after a meeting with his Nordic colleagues and the Ukrainian Minister of Defense on Nov. 21.

The outage had significant consequences. Funen Police deployed all available patrol cars, advising residents to approach officers directly if unable to reach them by phone. Officials recommended using phones from providers other than TDC or removing SIM cards to call 112, as phones can connect to emergency services without a SIM card. Customers with internet access were advised to use alternative communication methods like FaceTime and Facebook Messenger. TDC has not provided a timeline for resolving the issue.

Operational issues on TDC's mobile network affected Danish railway operator Banedanmark, which dealt with disruptions to the digital signaling system in Jutland on Thursday evening, as per a report by the Center for Cyber Security cited by TV2.

Affected lines included Esbjerg-Holstebro, Vejle-Struer, and Aarhus-Aalborg. This disruption highlights challenges in Denmark’s transition from analog to digital signaling, a project aimed at nationwide implementation by 2033.

Banedanmark’s deputy director Nicolai Smidt Sigsgaard later reported that the operator’s digital signal system was up and running again, meaning train operations could start running in Jutland. “Normal operations are not expected until Friday,” he added.

With services largely restored as of Thursday evening, Banedanmark still did not have a definite answer to what caused the problems with the trains in Jutland. The operator's deputy director told news agency Ritzau that investigations will take place in the coming days so that the cause can be clarified.