Why Switzerland is blocking 148 million unwanted calls

More than 148 million unwanted calls have already triggered action by Swiss telephone operators in 2026. The figure covers calls suspected of spam or number spoofing, a technique that makes an incoming call appear to come from a different telephone number. Operators expect the flow to rise further before the end of the year.

Swisscom alone reported 102 million calls involving suspected spoofing or spam. It blocked 65 million, anonymised 30 million and displayed a warning on a further 7 million. Sunrise reported more than 46 million calls blocked, anonymised or flagged between January and August, about 20% more than during the same period last year.

The figures show how much of the filtering now happens inside telecom networks, before a call reaches a customer’s handset. They also show why unwanted calls remain difficult to eliminate. Fraudsters can place calls at scale, alter the number shown to recipients and replace it quickly when operators identify a pattern. Swiss consumers may see fewer suspicious calls, but the systems handling them are processing a continuous stream of attempted contacts.

Number spoofing lets a caller hide behind a familiar-looking Swiss number. The number displayed on a phone is not reliable proof of who is calling. Fraudsters can manipulate caller identification so that an overseas call appears to come from a Swiss mobile, landline or business number.

That tactic can increase the chance that a recipient answers. A local-looking number may appear to belong to a bank, an insurer, a public service or a neighbour. Once connected, the caller may try to obtain personal information, payment details or access credentials. The source report does not identify individual scam campaigns, but it confirms that operators are treating spoofed numbers as a major part of the unwanted-call problem.

The scale of foreign misuse is clear in Sunrise’s figures. From January through August, the operator flagged more than 10 million calls from abroad because of suspected impersonation or misuse of a Swiss number. Since the start of the year, calls from abroad carrying a potentially falsified Swiss number must be blocked or passed on with an “unknown caller” message. The rule targets the false identity presented to the recipient, rather than every international call.

Swisscom’s response divides suspicious traffic into three categories: block it, hide its identity or warn the customer. The operator blocked 65 million calls this year, anonymised 30 million and marked 7 million with a warning. Each measure changes what the recipient can do with the call, while allowing the network to handle legitimate traffic that might resemble suspicious activity.

Sunrise has adopted a similar layered approach. It said its systems blocked, anonymised or flagged more than 46 million calls between January and August. That total was around one fifth higher than the previous year’s figure for the comparable period. Salt is also introducing an anti nuisance call mechanism that blocks, on average, around two in five incoming calls.

The operators do not publish identical categories, so their figures cannot be treated as a direct ranking of network performance. Swisscom’s total covers the year to the date of the report, while Sunrise’s figure covers January to August. The numbers do establish the breadth of the response: automated screening has become a routine part of Swiss voice services, rather than a small add-on for individual customers.

Fraudsters can change numbers faster than fixed blocking lists can keep up. Salt says the effectiveness of countermeasures declines when callers rapidly replace the numbers they display. Swisscom described the task as a “game of cat and mouse”, reflecting the constant cycle of detection, blocking and adaptation.

That cycle also explains why a suspicious call can still reach a customer after millions of other calls have been stopped. Filtering systems examine patterns across large volumes of traffic, including the relationship between the apparent number, the call’s origin and other signals available to the operator. A number that looks harmless in isolation may become suspicious when it appears repeatedly in unusual traffic.

The pressure is likely to increase during the final months of the year. Operators link seasonal growth in unwanted calls to the expiry of contracts and insurance policies. Those dates create opportunities for callers posing as companies seeking renewals or offering new deals. Customers should treat an unexpected request for passwords, codes, payment details or urgent action as a warning sign. A genuine organisation can be contacted through a verified number or official website rather than through details supplied during a suspicious call.

Consumers still make the final decision about whether a suspicious call becomes a scam. Network filters can block, anonymise or flag traffic, but no system catches every attempt. The safest response to an unexpected demand is to end the call and verify the organisation independently.

Do not share banking credentials, one-time verification codes, passwords or identity details with an unsolicited caller. If the caller claims to represent a bank, insurer, telecom operator or public authority, use the institution’s official website, customer portal or a statement to find its contact details. Do not rely on a number supplied during the call. A warning label or an “unknown caller” message should prompt caution, although the absence of a warning does not prove that a call is genuine.

Swiss operators will continue adjusting their systems as fraudsters alter their methods. Sunrise’s more than 10 million flagged foreign calls and Swisscom’s 102 million suspicious or spam calls illustrate the scale of the work already taking place. For customers, the practical lesson is straightforward: let unexpected calls go unanswered when appropriate, check the caller through an independent channel and report repeated abuse to the operator. That combination gives automated filters more information while reducing the chance of a costly mistake.