North Korea has long prohibited its people from interacting with South Korea. Recent reports suggest that the North Korean authorities have deployed new mobile signal detectors along the China-North Korea border to prevent residents from using Chinese mobile communication services to make unauthorized calls to South Korea.
According to Radio Free Asia, the North Korean authorities have provided high-performance handheld wireless signal detectors to border security personnel to further prevent residents from making unauthorized calls to South Korea using mobile phones.
A source in North Korea’s Pyongan Province told the radio station that officials from the National Security Bureau in Gyodong County received this new equipment last week. Gyodong County is located near the Chinese border, facing Dandong City in Liaoning Province.
The source mentioned that these handheld detectors are used to track North Koreans who are contacting their South Korean relatives using Chinese mobile phone numbers.
The brand labels of these devices have been removed, making their country of origin unclear, but the source described them as “high-performance tools with broad detection range capable of quickly capturing signals.”
Despite North Korea having smartphones, the government strictly separates domestic and international calls by managing the domestic network to maintain strict domestic surveillance. For the general public, making international calls is nearly impossible.
North Koreans must use government-monitored carriers to make legal international calls, but authorities can easily eavesdrop. Additionally, the Yanggakdo International Hotel in Pyongyang allows direct international calls but is only open to foreigners and senior North Korean officials.
Due to these restrictions, many North Koreans are unable to contact relatives living abroad or who have defected. In desperation, residents in border areas pay hefty fees to intermediaries to use China’s mobile network, often hiding in mountainous areas to avoid detection.
In theory, these wireless signal detectors can identify unauthorized communication sources by tracking the electromagnetic waves emitted during phone calls. Once a signal is detected, security personnel can track the user.
The source mentioned that these new devices have seen significant upgrades in speed and coverage compared to those used in previous years, being able to quickly and extensively identify the source of mobile signals. “The new handheld detectors can be used on the move, which is a cause for concern.”
A second source in Pyongan Province stated that authorities have intensified monitoring at the border. “Surveillance cameras have been installed in border areas. Local residents say the surveillance is stricter than ever before.”
The source noted that authorities are particularly focused on calls between local residents and relatives settled in South Korea. “Anyone found discussing rice prices with South Korean relatives will be labeled a spy.”
The source added, “Now, undercover agents patrol residential areas and densely wooded hillsides before sunrise, carrying devices in their pockets to detect illegal call signals.”
Previously, authorities could only detect illegal calls lasting over 5 minutes, but the new handheld detectors can identify calls as short as 1 minute.
A report released in 2024 by the South Korean government-funded think tank, the Institute for Unification Studies, highlighted that North Korean authorities strictly monitor and harshly punish individuals possessing and using Chinese mobile phones. In certain cases, North Koreans contacting South Korea using Chinese phones are classified as political prisoners and sent to political prisons.