It covers the legally regulated surveillance of telecommunications systems (in the Swiss setting: legal basis, organisation, request types, and providers), viewed from an investigation perspective — and it deliberately excludes postal surveillance and government spyware ("Govware").

Four things define the Swiss scope. The legal basis sets out what the law actually permits; the organisation is who runs the surveillance infrastructure; the request possibilities are the catalogue of measures investigators may ask for; and the providers are the telecom companies obligated to cooperate. Everything in this topic is one of these four pieces.

Two things are deliberately left out. Post (physical mail surveillance) is a separate regime, and Govware — state trojans or spyware installed on a device to read it before encryption — is a fundamentally different technique: it sits on the endpoint rather than tapping the network, so it can defeat end-to-end encryption that lawful interception cannot. Excluding it keeps the focus squarely on the network side.

The key framing is that this is lawful interception: surveillance conducted with legal authorisation, by the state, against telecom infrastructure, from the perspective of a criminal investigation. It is not hacking and not the covert exploits covered elsewhere in mobile security; it is the legally-sanctioned process by which police obtain telecom data.

Tip: Surveillance is an emotional, politically charged topic — but the engineering reality is a tightly regulated request-and-response system between authorities and telecom providers, with court oversight for the most intrusive measures.

Go deeper:

• Dienst ÜPF — official site (li.admin.ch) — the actual Swiss federal service that operates lawful interception, sitting between the requesting authorities and the providers; the authoritative source for exactly the Swiss scope this card describes.
• Das BÜPF / SPTA — the Swiss legal basis (li.admin.ch) — the Federal Act on the Surveillance of Post and Telecommunications (BÜPF, SR 780.1, in force since 1 March 2018), spelling out what may be requested and which providers must cooperate.
• Lawful interception (Wikipedia) — how authorised, court-ordered wiretapping is built into telecom networks, and how it differs from dragnet mass surveillance (kept: on-topic and feeds the image carousel).
• Tobias Engel — SS7: Locate. Track. Manipulate. (31C3, 2014) — the canonical CCC talk on how the network's own signalling (SS7) lets you locate and track any phone to ~50 m worldwide; shows what "surveillance against telecom infrastructure" really looks like in practice.

The BÜPF is the Swiss federal law on the surveillance of postal and telecommunications traffic ("Bundesgesetz betreffend die Überwachung des Post- und Fernmeldeverkehrs") — it defines the legal basis, scope, and obligations for lawful interception.

What the BÜPF establishes:

• The legal foundation for any telecom surveillance — without a statutory basis, surveillance would be unlawful
• The scope (Geltungsbereich) — which actors and which data fall under the law
• The obligations placed on telecom providers (the Art. 26–30 categories)

Why a dedicated law matters: surveillance is a serious intrusion into fundamental rights (privacy, secrecy of telecommunications). In a rule-of-law state, the police cannot simply demand data — every measure must be grounded in a specific legal authority, with the intrusiveness of the measure matched by the height of the legal hurdle (e.g., real-time content interception requires a court order, while a simple subscriber lookup does not).

Tip: Think of the BÜPF as the rulebook that answers "who may request what data, from whom, under which conditions." Every surveillance measure in this topic traces back to an article of this law.

Go deeper:

• The SPTA / BÜPF — Swiss legal basis (li.admin.ch) — the official surveillance service's page confirming the BÜPF/SPTA entered force 1 March 2018.
• Lawful interception (Wikipedia) — how a dedicated legal regime authorises and bounds state interception, vs dragnet surveillance.