Mysterious Number Station Broadcasts Linked to US Military Base in Germany

A rhythmic recitation of numbers, punctuated by the Persian word for “Attention!” (“Tavajoh!”), has been broadcasting repeatedly on a shortwave radio frequency since the start of the U.S.-Israel military operation against Iran on February 28. The broadcasts, airing twice daily, have prompted investigation into their origin and purpose.

Priyom, an organization that monitors global military and intelligence use of shortwave radio, identified the signal’s source as a U.S. Military base in Böblingen, Germany. Using radio-location techniques, Priyom traced the transmissions to a facility within a restricted training area between Panzer Kaserne and Patch Barracks, potentially linked to the U.S. Army’s 52nd Strategic Signal Battalion, according to a statement released by the organization.

The broadcasts consist of two-hour segments, each beginning with “Tavajoh!” followed by strings of numbers in Persian, occasionally interspersed with English words. Five days after the initial broadcasts began, attempts were made to jam the frequency, prompting a shift to 7842 kHz the following day, Priyom reported.

Experts in radio communications believe the transmissions are likely an example of a “number station”—a shortwave radio broadcast used to deliver encrypted messages. “We see an encrypted radio message used by foreign intelligence services, often as part of a complex operation by intelligence agencies and militaries,” explained Maris Goldmanis, a Latvian historian and researcher specializing in number stations.

Number stations have historically been associated with espionage, providing a discreet method for intelligence agencies to communicate with operatives in the field. “For intelligence agencies, it is important to communicate with their spies to gather intelligence,” said John Sipher, a former U.S. Intelligence officer who served 28 years in the CIA’s National Clandestine Service. “This is not always possible in person due to political constraints or conflict. This is where number stations come in.”

While the use of number stations dates back to the First World War, they gained prominence during the Cold War. Governments utilized automated voice transmissions of coded numbers to communicate with agents, often employing Morse code or two-way communication systems, according to Goldmanis, citing declassified documents from the KGB and CIA.

Sipher noted that while modern communication technologies like satellites and encrypted systems are now prevalent, number stations offered a method of covert communication during periods when such technologies were less accessible. The apparent randomness of the numbers necessitates a codebook for decryption, he added. “Nobody can make heads or tails of it or understand what it says unless you have the codebook that can give you hints to decrypt the code,” he said, emphasizing the need for pre-established coordination and systems.

The origin of the signal has been identified, but the purpose of the broadcasts and the intended recipients remain unknown. The structured nature of the transmissions—their consistent schedule and frequency usage—suggests a planned operation, according to Priyom. As of March 23, 2026, the U.S. Government has not commented on the broadcasts, and the transmissions continue on the 7842 kHz frequency at 02.00 UTC and 18.00 UTC daily.