North Korean phones are screened by the Ministry of State Security first to prevent them from being used in any non-permitted ways, so cannot be used to communicate with those in other countries.
Because of this, North Koreans use Chinese-made phones that have been purchased from smugglers, and contact relatives through an app WeChat, allowing voice calls, text messages, and video calls.
WeChat is also used to send money to loved ones in North Korea so they can maintain a living and eat their next meal. The transfer process involves the money passing through several countries before reaching the recipient in North Korea. After initial links are established through these networks in both North and South Korea, money is sent to the account of a Chinese middle-man, who takes a cut for themselves.
There are many shops in the China-North Korea border regions that are jointly run by people from both countries. At such places, at a pre-arranged time and date, the money originally sent by the defector is given over to the North Korean broker. The transfer is conducted not in South or North Korean won but in Chinese yuan.
The North Korean broker then takes their cut before taking the money and delivering it to the other side of the border.
After all is said and done, around seventy percent of the original amount makes its way into the hands of the recipient. Some unscrupulous brokers, however, take more, leaving only around half of the original sum.