North Korea has recently begun to use recorded phone calls to improve efforts to track down international callers, Daily NK has learned.

“Signal detection units have recently started to focus on select areas with phone tapping devices to identify signals and record phone calls,” a North Pyongan Province-based source told Daily NK yesterday. 

“The units then alert local inminban leaders and agents from the Ministry of State Security [MSS] to have them listen to the recordings to confirm the voices of the callers,” he continued.  

“After the callers are identified, the authorities head to the residences of the callers and play the recording to them before making arrests,” the source added, further noting that callers caught in this situation are unable to make excuses about their actions or run away. 

North Korea has traditionally identified caller locations by detecting signals exchanged between mobile devices and cellular base stations. The accuracy of this method increases when there are many cellular base stations clustered together; this, however, is not the case in North Korea. 

The authorities have also faced challenges in clearly identifying callers when there are other callers nearby or a suspected international caller provides “excuses” about why they made their calls. 

The use of recorded calls has made it almost impossible for international callers to escape crack downs by the authorities. 

North Korea announced in late 2019 that it had developed a “spectrum analyzer” that could track mobile call signals and convert them into audio recordings. 

The country’s security authorities are very likely using these new devices in their international caller tracking operations. 

Daily NK’s source said that surveillance teams are using their new technology-based tools to identify and arrest international callers, regardless of their social status. 

“At least seven or eight people were arrested in Siniju from the second week of April until now for making international calls with Chinese traders,” the source said. 

“These efforts are more than just an attempt to scare other people out of making international calls. The authorities are really cracking down hard,” the source continued.

The authorities are reportedly focusing their crackdowns on mobile devices using Chinese telecommunications networks, which means “it’s hard for people to speak on the phone for more than a minute and a half,” the source explained.  

“People could hold 50 calls a day [with Chinese traders] in the past, but now they’re finding it hard to make even one,” he added. 

“There are no exceptions for powerful people, either,” the source continued. “Even members of the MSS and the military, as well as the donju [North Korea’s wealthy entrepreneurial class] can’t escape the crackdowns.” 

The authorities appear to be conducting these intense crackdowns as part of efforts to stop smuggling and the flow of information across the Sino-North Korean border.

“The North Korean authorities are taking smuggling with China as well as contact with the outside world very seriously,” the source said. “The crackdowns will likely continue because their purpose is to prevent the spread of COVID-19.” 

*Translated by Violet Kim

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Mun Dong Hui is one of Daily NK's full-time journalists. Please direct any questions about his articles to