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Hazard · Technical

Communication failure

Stay calm – outages are usually regional and limited in time. Use a battery- or crank-powered FM radio for official information and fall back on your cash reserve and contact details on paper. Emergency numbers often still work when the normal network has already failed – dial 112 if in doubt.

Whether a cyberattack on a provider, a major technical disruption or a power outage that paralyses the mobile-phone antennas: when the internet, mobile networks or payment systems fail, important processes need an analogue fallback. Today almost everything depends on the network — communication, payment, navigation, information.

Mobile masts have only a limited backup-power reserve; during a larger power outage, the mobile network therefore often fails as well. Cyberattacks can hit individual providers or whole sectors. The Federal Office for Cybersecurity (NCSC) continuously records such incidents in Switzerland.

Preparation is simple: important numbers and addresses on paper, a cash reserve, a battery- or crank-powered FM/DAB+ radio as an information channel — and the knowledge that emergency numbers often still work when the normal network has already failed.

Risk rating

Risk · High (level 4 of 5)

Likelihood: High · Impact: Medium → Overall risk: High.

Risk matrix: likelihood runs vertically (top = high), impact runs horizontally (right = high). The highlighted cell shows this hazard's rating.
Impact
Low Medium High
High This hazard's rating
Medium
Low

Legend: Low (green) · Medium (yellow) · High (red). Overall risk is likelihood multiplied by impact.

Cyberattacks or technical disruptions can knock out the internet, mobile networks and payment systems over a wide area.

Immediate measures

  • Important contacts on paper
  • Keep a cash reserve
  • FM radio as a fallback

Warning signs

  • No mobile reception or "emergency calls only" on the display although the battery is full
  • Internet, online banking or card payment fail at the same time (indication of a provider/system disruption)
  • NCSC warnings or media reports about ongoing cyberattacks / major disruptions
  • A cluster of suspicious phishing messages (often around or in the wake of major disruptions)
  • Power outage in the neighbourhood — as a precursor to a subsequent mobile-network failure

Before · During · After

Before

  • Important numbers and addresses on paper
  • Cash reserve in small denominations
  • FM radio ready as an information channel
  • Consider radio alternatives (PMR, mesh)

During

  • Stay calm – outages are usually limited in space and time
  • Emergency numbers often still work – when in doubt, 112
  • Follow official information via radio

After

  • Change passwords if accounts are affected
  • Expect phishing waves after disruptions

This really happened

  1. 2023 Swisscom mobile network outage

    On the morning of 14 December 2023, calls, SMS and mobile internet were disrupted for many Swisscom customers for around two and a half hours, including in Zurich, Bern, Lucerne and Basel.

    Source

  2. 2021 Nationwide emergency-number outage

    On the night of 9 July 2021 the emergency numbers 112, 117, 118 and 144 were unreachable for several hours in almost all cantons; Swisscom cited a fault in the business telephony platform.

    Source

  3. 2020 Swisscom emergency-number outages

    In spring 2020 the emergency numbers failed repeatedly (including on 17 January) in almost all cantons; the frequency of these incidents led to an OFCOM investigation and a report to Parliament.

    Source

  4. 2003 Italian blackout

    The power outage of 28 September 2003, triggered by a Swiss line, paralysed not only the electricity but also the telephone and mobile networks across large parts of Italy and showed the dependence of communications on electricity.

    Source

Frequently asked questions

How do I prepare for a communication outage?

Write down important numbers and addresses on paper and keep a cash reserve in small denominations. Have an FM radio ready as an information channel and check radio alternatives such as PMR or mesh.

How do I recognise a communication outage?

Signs include no mobile reception or "emergency calls only" on display despite a full battery, as well as simultaneous failure of internet, online banking and card payment. Often a power outage in the neighbourhood precedes it, because the mobile antennas fail afterwards.

What should I do after an outage?

Change passwords if accounts could be affected and expect phishing waves in the aftermath of major outages – suspicious messages often increase after such incidents.

Official sources