The nationwide disruption to telephony and the fixed network on Friday morning, January 17, 2020 also restricted Certas. As a result, our employees were no longer able to take calls from Swisscom. Certas was not available by telephone for customers and partners. 

Alarms from alarm systems were received; we had no restrictions here. Incoming alarm messages could be processed to a limited extent. We tried to reach people via mobile phones (no IP telephony). Certas could not take any measures, Swissom informed about the situation. 

Further information can be found here.