• Signals intelligence units and formations (1 C, 8 P)

*

• Directors of signals intelligence agencies (2 C, 1 P)

D

• Directorate-General for External Security (2 C, 12 P)

G

• GRU (2 C, 14 P)

W

• Signals intelligence agencies of World War II (13 P)

0–9

• 7th Signal Regiment (Australia)

A

• Agencia Nacional de Inteligencia
• Australian Cyber Security Centre
• Australian Signals Directorate

C

• Communications Security Establishment
• Cipher Bureau (Poland)
• Communications and Cybersecurity Troops
• Communications & Information Services Corps

D

• Defense Intelligence Headquarters
• Directorate General for External Security
• DRSD

F

• Finnish Defence Intelligence Agency

G

• GCHQ
• GCHQ Bude
• General der Nachrichtenaufklärung Training Referat
• Government Communications Security Bureau
• GRU (Soviet Union)

I

• Information Network Security Agency
• International Liaison Department of the Communist International

J

• Joint Cipher Bureau
• Joint Sigint Cyber Unit

L

• LOVEINT
• Luftnachrichten Abteilung 350

M

• MI8

N

• Nacionalna služba elektroničkog izviđanja
• National Communications Centre
• National Cyber Security Centre (Ireland)
• National Defence Radio Establishment
• National Security Agency
• National Security Operations Center
• National Telecommunication Monitoring Centre
• Nationale SIGINT Organisatie

P

• Pers Z S

R

• Serviciul de Telecomunicații Speciale
• FAPSI
• Russian Signal Troops

S

• Signals Intelligence Agency
• Special Communications Service of Russia
• State Special Communications Service of Ukraine

U

• UKUSA Agreement
• Uppland Regiment (signals)