Identification of the calling line
The technical and administrative regulation concerning the identification of the calling line sets out the requirements for telecommunications service providers on transmitting the calling line number.
New requirement in the fourth edition (applies to landline numbers from 1 January 2026 and mobile numbers from 1 July 2026):
Transit providers must insert an indicator to mark incoming calls from abroad containing a Swiss telephone number. The identification must also give the name of the transit provider that has carried out the identification. If the call cannot be identified on technical grounds, the transit provider must remove the caller number (requirement 2, chapter 5).
This enables the terminating provider to better recognise calls with spoofed numbers and, in accordance with Article 26a paragraph 6 OTS, to remove the number of the calling line for the line being called or to block the call entirely.
The technical and administrative regulations concerning the identification of the calling line (SR 784.101.113/1.7; de, fr, it) can be found here.
Details on the technical implementation can be found in asut's Swiss TSP Anti-Spoofing Agreement Technical Specification.