•
Schengen Information System, in Europe •
Security Information Service, Czech domestic information intelligence agency known as
BIS •
Secret Intelligence Service, UK intelligence agency, also known as
MI6 •
Australian Secret Intelligence Service, Australia’s national intelligence service •
Canadian Security Intelligence Service, Canada's national intelligence service •
New Zealand Security Intelligence Service, an intelligence agency of the New Zealand government •
Finnish Security Intelligence Service, the intelligence agency of Finland in charge of national security •
Slovenská informačná služba, Slovak Intelligence Service •
Special Intelligence Service, a secret FBI intelligence agency operating in South America during World War II •
Signals Intelligence Service, the former United States Army codebreaking division •
Information and Security Service of the Republic of Moldova, the principal intelligence agency of Moldova. •
Serviço de Informações de Segurança, a Portuguese intelligence agency •
Survey of India Service, formerly the Great Trigonometric Survey •
Special Investigation Section, a
tactical detective and
surveillance unit of the
Los Angeles Police Department • Signals Intelligence Section, involved with the
Magic project during World War II == Businesses ==