State-owned Bane Nor, Norway's equivalent of the Swedish Transport Administration, tells Norwegian TV 2 that problems with its communication system are related to problems at Telenor.
This will take a while, says Bane Nor press officer Olav Nordli.
The telephone problems are also making it difficult to reach Norway's three emergency numbers: 110, 112 and 113. The cause of the fault is still unclear, but Aftenposten reports that it is not due to hacking.
There are no indications that any attacks are underway, Telenor press spokesperson Vetle Andersen tells the newspaper.
