In May this year, a North Korean defector in her 40s took a call from an unknown number at her office in the South Korean capital Seoul.
It was from her brother, who she had not seen for more than a decade, calling illegally from North Korea after tracking her down.
He was speaking from a remote mountainside near the border with China, and was in dire need of money to help treat another sister's late stage cancer, she said.
Accompanied by a Chinese broker, the brother had spent five hours climbing up the mountain, avoiding North Korean security and desperately searching for a signal on a Chinese mobile telephone.
Contact with anyone in the South is punishable by death in North Korea, one of the world's most isolated states.
The broker was part of a growing group of people, mostly Chinese of Korean descent, who use ties on both sides of the border to funnel money to the North, an illegal and highly dangerous operation.
At first, the defector in the South suspected a trick and demanded the caller answer a question that only her brother could know the answer to.
"I asked him to tell me the name of the train station where we were separated. I am now 40 and we were separated when I was 26," she said, requesting anonymity for fear of reprisals against her family. "Then he said he needed money."
Image: A North Korean defector living in South Korea who requested to be known only by surname, Im, and her whole face not to be photographed, uses her mobile phone.
Text: Ju-min Park, Reuters