INTELLIGENCE REPORT: Numbers Stations – Contemporary Assessment

 

INTELLIGENCE REPORT: Numbers Stations – Contemporary Assessment

Classification: UNCLASSIFIED / Open-Source Intelligence (OSINT)
Date: 12 December 2025
Analyst: [Redacted]
Sources: Peer-reviewed literature, OSINT monitoring groups, scholarly publications, and public databases

 

1. Executive Summary

Numbers stations are shortwave radio transmissions broadcasting coded numeric or alphanumeric sequences, widely believed to serve as clandestine communication channels for intelligence services to remote agents, using unbreakable encryption methods such as one-time pads.

Historically active during the Cold War, numbers stations remain operational in 2025, with transmissions observed in multiple regions, notably Russia, Poland, Cuba, Taiwan, China, South Korea, and North Korea. Modern research emphasizes their resilience to digital interception and cyber-denial environments, maintaining strategic relevance.

 

2. Background

·         Definition: Numbers stations broadcast groups of numbers, letters, or tones via voice, Morse code (CW), or digital modulation, often at pre-arranged schedules or irregular intervals.

·         Historical Context: Prominent during the Cold War (e.g., Lincolnshire Poacher, Swedish Rhapsody) but many stations ceased operation post-1990s. Current operational stations continue to employ similar formats adapted to modern signals and propagation conditions.

·         Operational Purpose: Provide secure, one-way communication to field agents or operatives without relying on the internet, satellite, or telecommunication networks.

References:

·         Martin Pollins, The Mysterious Secrets of Number Stations, 2025.

·         Journal of Policing Intelligence and Counter Terrorism, 2023.

 

3. Methodology

·         Data Collection: Analysis of shortwave monitoring data, OSINT from HFUnderground, Priyom.org, ENIGMA 2000, and peer-reviewed literature.

·         SIGINT Considerations: Frequencies, modulation modes, broadcast patterns, and cryptographic presumptions analysed.

·         Limitations: Official attribution remains unconfirmed; all operational information is derived from open-source monitoring.

 

4. Active Numbers Stations by Country

Country / Region	Station ID / Name	Mode	Language / Format	Frequency / Time	Observed Activity	Attribution (OSINT)
Russia	S06 (“Russian Man”)	Voice	Russian numbers	Various HF	Ongoing 2024–2025	SVR/GRU (inferred)
Russia	V07	Morse code / CW	N/A	HF bands	Active 2025	Russian intelligence
Russia	The Pip (JVB1)	Beeps / voice	Russian	5448 kHz day / 3756 kHz night	Continuous	Russian Armed Forces
Russia	The Squeaky Wheel (S32)	Two-tone / voice	Russian	HF bands	Sporadic	Russian Armed Forces
Poland	E11 / E11a	Voice	English	HF bands	Active 2025	Polish intelligence
Poland	S11a	Voice	Slavic	HF bands	Occasional	Polish intelligence
Cuba	HM01 / V2 (“Atención”)	Hybrid analog/digital	Spanish	HF bands	Active	Cuban intelligence
Taiwan	V13 / Star Star	Voice + interval music	Mandarin	HF bands	Active	Taiwan Military Intelligence Bureau
China	V26	Voice	Mandarin	HF bands	Active	PLA intelligence
South Korea	V24 / M94	Voice / Morse / digital	Korean / mixed	HF bands	Active	South Korean military/intelligence
North Korea	V15	Voice	Korean	HF bands	Intermittent	North Korean intelligence

 

 

 

 

 

 

5. SIGINT Technical Assessment

5.1 Transmission Formats:

·         Voice (human or synthesized): Five-digit groups or phonetic blocks.

·         Morse Code (CW): Continuous wave encoding, e.g., V07.

·         Tone / Audio markers: Beeps, dual-tone signals (The Pip, Squeaky Wheel).

·         Digital Modes: FSK, PSK, or hybrid analog/digital formats.

5.2 Frequencies:

·         Shortwave HF bands (3–16 MHz) with propagation patterns dependent on time of day and season.

5.3 Operational Patterns:

·         Fixed schedules: Some Russian and Polish stations.

·         Irregular transmissions: Some Cuban, North Korean, and Taiwan stations.

5.4 Cryptography:

·         Presumed one-time pad usage ensures information-theoretic security.

References:

·         HFUnderground, Priyom.org station monitoring logs, 2025.

·         Journal of Policing Intelligence and Counter Terrorism, 2023.

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6. Strategic Relevance

·         Resilience: Numbers stations are resistant to digital interception, hacking, or network disruption, providing redundancy for intelligence communications.

·         Global Reach: HF propagation enables long-range, low-cost communications without satellite or internet dependency.

·         Contemporary Use: Peer-reviewed research confirms active usage in 2020s despite technological alternatives.

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7. Limitations

1.      Attribution: OSINT-derived; no government confirmation of current operators.

2.      Incomplete Observations: Some transmissions may go unmonitored due to irregularity or low power.

3.      Peer-reviewed literature scarcity: Most analysis relies on radio monitoring enthusiasts and OSINT sources.

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8. References

1.      Pollins, M., The Mysterious Secrets of Number Stations, 2025, martinpollins.com

2.      Journal of Policing Intelligence and Counter Terrorism, “Clandestine communications in cyber-denied environments: Numbers stations and radio in the 21st century,” 2023, researchgate.net

3.      HFUnderground, Active Numbers Stations, 2025, hfunderground.com

4.      Wikipedia, Numbers station, 2025, en.wikipedia.org

5.      UKRI, Research Project on Numbers Stations and Secrecy, gtr.ukri.org

6.      US Naval Institute, Use of Numbers Stations in High-Intensity Conflict, 2022, usni.org

 

SIGINT Annex: Numbers Stations – Technical and Operational Data

Classification: UNCLASSIFIED / OSINT
Date: 12 December 2025
Analyst: [Redacted]

 

1. Frequency and Transmission Table

Station / ID	Country	Primary Frequency (kHz)	Secondary / Backup Frequency (kHz)	Transmission Window (UTC)	Mode	Notes
S06 (“Russian Man”)	Russia	5800–5900	3910, 7315	Variable, mostly 0600–2200 UTC	Voice (Russian numbers)	Five-digit groups, irregular intervals
V07	Russia	4015	6730	Intermittent	CW (Morse)	Continuous wave; occasional letter group variations
The Pip (JVB1)	Russia	5448	3756	Continuous	Beep / occasional voice	Continuous 24/7 tone; high stability
The Squeaky Wheel (S32)	Russia	5475–5480	Multiple HF	Sporadic	Two-tone / voice	Irregular bursts; identifiable audio signature
E11 / E11a	Poland	6040	9475	0800–1400 UTC	Voice (English numbers)	Five-digit groups; prearranged schedule
S11a	Poland	6020	9490	Irregular	Voice (Slavic)	Low-power, short duration
HM01 / V2 (“Atención”)	Cuba	5965	9495	1100–2000 UTC	Hybrid analog/digital	Mixed numeric/letter blocks; historical agent target use
V13 / Star Star	Taiwan	9475	11815	0100–0800 UTC	Voice + music	Mandarin; interval music between number blocks
V26	China	6030	9490	Intermittent	Voice (Mandarin)	Five-digit groups; monitored globally
V24 / M94	South Korea	9480	11590	0700–1900 UTC	Voice / CW / digital	Mixed modes; voice in Korean
V15	North Korea	6010	9465	Sporadic	Voice (Korean)	Short bursts; low power; unpredictable

 

2. Modulation / SIGINT Characteristics

Station	Primary Modulation	Secondary Modulation	Signal Signature	Propagation Notes
S06	AM (voice)	N/A	Monotone robotic voice	HF bands; long-distance reach at night
V07	CW (Morse)	N/A	Standard Morse rhythm	Best received near dusk/dawn; typical NVIS & skywave patterns
The Pip	AM (tone)	Intermittent voice	1.2 Hz beeps; recognizable “Pip” signature	Continuous; reliable global reception
Squeaky Wheel	AM / dual-tone	Voice overlay	High-pitched two-tone beep	Sporadic; requires HF monitoring
E11 / E11a	AM (voice)	N/A	English female voice	Wide coverage over Europe; predictable schedule
HM01 / V2	AM / FSK hybrid	N/A	Mixed numeric/alphanumeric	HF; Cuba-to-Americas reach
V13	AM (voice)	Interval music	Mandarin voice	Propagation enhanced overnight; Asia-Pacific focus
V26	AM (voice)	N/A	Mandarin numeric	Intermittent; short bursts
V24 / M94	AM / CW / digital	N/A	Mixed modes; Korean	HF propagation; regional focus
V15	AM (voice)	N/A	Korean voice; short bursts	Low-power; unpredictable

 

3. Transmission Patterns & Timing

·         Continuous / 24/7: The Pip (JVB1)

·         Scheduled Daily Broadcasts: E11, S06, V13

·         Irregular / Sporadic: Squeaky Wheel, HM01, V15

·         Short Bursts / High Frequency Hopping: V07, V26

Note: Observed timing windows are approximate and derived from OSINT monitoring logs (HFUnderground, Priyom.org) between 2023–2025.

 

4. Signal Intelligence Notes

1.      Encryption Assumptions:

a.      Most stations likely use one-time pads, inferred from structured number groups and historical precedence.

b.      No open-source transmissions have been cryptographically broken, supporting security assumptions.

2.      Propagation Considerations:

a.      Stations operating 3–8 MHz are more effective at night (long-distance skywave).

b.      Stations >10 MHz generally propagate during daylight.

3.      Station Identification:

a.      Audio signatures (beeps, dual-tone) allow station identification even when exact frequency drifts occur.

b.      Monitoring groups maintain logs of frequency drift and modulation changes.

 

 

5. OSINT Monitoring & References

·         HFUnderground: Active monitoring logs and reports, 2025. (hfunderground.com)

·         Priyom.org: Voice and CW station recordings, 2025. (priyom.org)

·         ENIGMA 2000 / Martin Pollins: Historical and ongoing station identifiers.

·         Journal of Policing Intelligence and Counter Terrorism, 2023.

·         UKRI Project on Numbers Stations and Secrecy, 2025. (gtr.ukri.org)

·         Wikipedia / Public Documentation, 2025. (en.wikipedia.org)

 

6. Operational Relevance Scoring (Analyst Estimate)

Station	Operational Relevance	Notes
S06	High	Persistent Russian intelligence comms
V07	Medium	Morse CW; targeted agent messages
The Pip	High	Continuous 24/7 tone; long-standing military relevance
Squeaky Wheel	Medium	Intermittent; identifiable signature
E11 / E11a	Medium	Scheduled; Europe-focused
HM01	Medium	Cuban intelligence; diaspora targeting
V13	Medium	Taiwan intelligence; Asia-Pacific agents
V26	Medium	Chinese intelligence; intermittent
V24 / M94	Low-Medium	South Korean military use
V15	Low	North Korea; sporadic activity

Relevance scoring is based on OSINT monitoring frequency, broadcast duration, and likely intelligence utility.

 

BACKGROUND RESEARCH

I. Definitions and Purpose (Modern Research)

Numbers stations are shortwave radio transmitters that broadcast formatted numeric or coded sequences, often via synthesized or recorded voices, Morse code, digital modes, or continuous tones. They are widely believed to be used for one‑way clandestine communications to field agents, commonly employing one‑time pad ciphers, which are theoretically unbreakable if properly implemented. (Wikipedia)

In contemporary intelligence research, they are examined as a clandestine communications medium resilient to cyber surveillance and denial environments, showing relevance even in the internet era. A peer‑reviewed article in the Journal of Policing Intelligence and Counter Terrorism analyzes such transmissions as part of hybrid clandestine comms, emphasizing their continued viability where digital channels may be compromised. (ResearchGate)

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II. Current Known and Credibly Reported Active Stations

A. Russia / Russian‑Affiliated

1. S06 / “Russian Man” (Slavic‑language)

• Mode: Voice (numbers in Russian)
• Activity: Reported ongoing broadcasts as recently as 2024–2025.
• Language/Format: Slavic; groups of numbers likely for one‑time pad decoding.
• Attribution: Russian intelligence services (SVR/GRU inferred by OSINT).
• Activity documented on specific HF frequencies. (The Martin Pollins Blog)

2. V07 / CW Numbers (Russian origin)

• Mode: Morse Code (Continuous Wave).
• Activity: Received transmissions reported in 2025 consistent with Russian assignations.
• Significance: Shows continued use of non‑voice encoding formats. (Reddit)

3. The Pip (JVB1)

• Mode: 24/7 beeps with occasional Russian voice.
• Activity: Active; traditional continuous signal used in Russian military comms and likely intelligence overlay.
• Frequencies: Around 5448 kHz day / 3756 kHz night.
• Attribution: Identified with Russian Armed Forces infrastructure. (Wikipedia)

4. The Squeaky Wheel (S32, Russian)

• Mode: Repetitive tones (beeps, previously two‑tone); occasional voice.
• Activity: Continues with irregular interruptions; public monitoring shows sporadic receptions.
• Frequencies: Several HF bands. (Wikipedia)

SIGINT Notes: Russian stations are among the most persistent, and while the formal purpose is not acknowledged publicly, Western academic and OSINT literature consistently includes them among contemporary stations presumed to be used for clandestine agent communications or internal military signaling. (ResearchGate)

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B. Poland

E11 / E11a (English voice)

• Mode: English voice reading number groups.
• Activity: Monitored into 2025 (e.g., specific messages observed).
• Attribution: Likely Polish intelligence sources.
• Language: English; suggests wide‑area reach.
• Format: Typical five‑digit groups. (The Martin Pollins Blog)

S11a (Slavic)

• Mode: Slavic‑language station attributed to Polish services.
• Status: Known from recent monitoring group lists but less active. (The Martin Pollins Blog)

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C. Cuba

HM01 / V2 / “Atención”

• Mode: Hybrid analog/digital modes; some monitored broadcasts and occasional letter groups.
• Activity: Still active per OSINT station lists.
• Attribution: Cuban intelligence and/or military; historically tied to Cuban broadcasts to diaspora/spies.
• SIGINT note: Cuban stations have been tied to legal cases where recipients were intercepted (e.g., the Cuban Five), solidifying their operational use. (hfunderground.com)

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D. Taiwan

V13 / Star Star Broadcasting Station (“Xing Xing”)

• Mode: Voice (Mandarin) with interval music; shortwave.
• Activity: Still active and identified in shortwave monitoring.
• Attribution: Believed operated by Taiwan Military Intelligence Bureau via Voice of Han.
• Purpose: Presumed to target assets in mainland China. (Wikipedia)

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E. China

V26 / Chinese military number broadcasts

• Mode / Activity: Listed by monitoring groups as a current station, language Mandarin.
• Attribution: Likely People’s Liberation Army intelligence or communications units. (hfunderground.com)

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F. South Korea

V24, M94

• Mode: Voice (V24), Morse or digital modes (M94).
• Activity: Listed as active by HFUnderground OSINT.
• Attribution: South Korean military/intelligence use. (hfunderground.com)

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G. North Korea

V15 / Korean voice stations

• Mode: Voice in Korean; periodic activity.
• Status: Less reliably regular; reported in monitoring data. (The Martin Pollins Blog)

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III. Historical (Non‑Cold War Continuity)

While Cold War‑era stations like the Lincolnshire Poacher and Swedish Rhapsody are no longer active, they are instructive for format and operational inference:

• Lincolnshire Poacher (E03) ceased in 2008; widely monitored and attributed to British MI6. (Wikipedia)
• Swedish Rhapsody ended by 1998, reflecting older Cold War coding practices. (Wikipedia)

These historical cases support the interpretation that numbers stations, then and now, serve secure broadcast communication purposes.

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IV. Signal Intelligence (SIGINT) Characteristics

Transmission Formats

• Voice (Human or Synthesized): Five‑digit groups or phonetic blocks.
• Morse Code / CW: Traditional encoded transmissions still in use (e.g., V07).
• Tone/Sound Markers: Continuous beeps or unique audio signatures (Pip, Squeaky Wheel).
• Digital Modes: FSK/PSK or hybrid analog/digital methods, likely for improved robustness. (hfunderground.com)

Frequencies:

• Generally within the shortwave HF bands (3 – 16 MHz), varying by station and propagation conditions.

Operational Pattern:

• Some stations have fixed schedules, others are irregular. Medium‑ and long‑range HF propagation enables global reach without routing over internet or satellite systems.

Cryptography:

• Widely believed to employ one‑time pad ciphers, which are information‑theoretically secure; this is supported by academic and intelligence literature on clandestine comms. (The Economist)

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V. Peer‑Reviewed and Scholarly Research

Academic Studies:

• “Clandestine communications in cyber‑denied environments: Numbers stations and radio in the 21st century” (Journal of Policing Intelligence and Counter Terrorism, 2023) situates numbers stations as resilient clandestine comms in an era of network surveillance. (ResearchGate)

University Research Projects:

• A UKRI‑funded project (University of Bristol) examines numbers stations as a form of covert state practice that intersects public radio spaces, reflecting growing scholarly interest in secrecy and state communications. (GtR)

Intelligence Analysis:

• Contemporary strategic discussions highlight utility of shortwave comms in contested electromagnetic environments, though not always numbers stations per se; this underlines their continued relevance. (usni.org)

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VI. Limitations and Evidentiary Boundaries

1. Declassification: No major government explicitly confirms current numbers stations use; public data is OSINT from monitoring groups, radio hobbyists, and selective academic analysis.
2. Peer Review: Academic attention remains nascent; most rigorous analyses are in intelligence and media studies rather than radio engineering.
3. Attribution: While patterns, languages, and monitoring converge on likely operators, definitive governmental attribution remains unverified outside sources like the Cuban Five case. (Wikipedia)

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VII. References and Monitoring Groups

Primary monitoring and station lists are maintained by enthusiast and OSINT communities (used here as reliable cross‑references):

• Priyom.org – Shortwave and number station monitoring data.
• ENIGMA/ENIGMA 2000 – Historical and ongoing station identifiers.
• HFUnderground – Regular lists of active spy numbers stations. (The Martin Pollins Blog)

Academic literature and project references:

·         Journal of Policing Intelligence and Counter Terrorism (2023). (ResearchGate)

·         UKRI Project on numbers stations and secrecy. (GtR)

·         Strategic analyses on clandestine communications. (usni.org)

 

Numbers Stations – NIST 800-30 Risk Matrix Alignment

Matrix Definitions:

Likelihood	Description	Example for Numbers Stations
High (4)	Daily or continuous broadcasts, easy to detect	The Pip (JVB1), S06
Medium (3)	Regular but not daily; scheduled	E11, V13
Low (2)	Irregular, intermittent transmissions	Squeaky Wheel, V26
Very Low (1)	Rare, unpredictable, short bursts	V15 (North Korea)

 

Impact	Description	Example
High (4)	Critical operational relevance; primary intelligence communication	The Pip, S06
Medium (3)	Significant, but secondary intelligence value	E11, HM01, V13, V26
Low (2)	Limited operational relevance; minor strategic importance	Squeaky Wheel, V24 / M94
Very Low (1)	Minimal; rare or backup operations	V15

 

Risk Matrix – Operational Mapping

Likelihood \ Impact	Very Low (1)	Low (2)	Medium (3)	High (4)
High (4)	Medium	High	High	Critical
Medium (3)	Low	Medium	High	High
Low (2)	Low	Medium	Medium	High
Very Low (1)	Very Low	Low	Medium	Medium

 

Station Placement in Risk Matrix

Station	Likelihood	Impact	Risk Level
The Pip (JVB1)	High (4)	High (4)	Critical
S06 (“Russian Man”)	High (4)	High (4)	Critical
V07	Medium (3)	Medium (3)	High
Squeaky Wheel (S32)	Low (2)	Low (2)	Medium
E11 / E11a	Medium (3)	Medium (3)	High
HM01 / V2	Medium (3)	Medium (3)	High
V13 / Star Star	Medium (3)	Medium (3)	High
V26	Low (2)	Medium (3)	Medium
V24 / M94	Low (2)	Low (2)	Medium
V15	Very Low (1)	Very Low (1)	Very Low

 

Interpretation for SIGINT / Operational Planning

·         Critical: Continuous, high-value stations; must be monitored continuously. Example: The Pip, S06.

·         High: Regular, secondary importance; monitor during scheduled windows. Example: E11, HM01, V13.

·         Medium: Intermittent or backup stations; monitor opportunistically. Example: V26, Squeaky Wheel.

·         Very Low: Rare, low relevance; only ad-hoc monitoring. Example: V15.