A cellphone smuggled into North Korea helped Lee Seo Yeon take on two missions: one emotional, one financial. But at first, she feared there might be some mistake.

Listening in Seoul, the 40-year-old defector didn't recognize the voice on the other end. It was supposed to be a sister she hadn't spoken to since late 1998, when Lee left her family and waded through chilly, chest-deep waters to enter China.

Lee's sister is not much older than she is, but the voice on the phone "sounded like an old woman's," she said.

"But she remembered the scars I've got on my hip from when she asked me to sit on the edge of a chopstick for fun when we were little girls. She still remembers the name of my friend who lived next door. We talked about things like that, and I ended up crying."

Once Lee was certain she was talking to her sister, a broker took the phone on the North Korean end. Lee transferred 2 million won ($1,880) to a South Korean bank account belonging to a Korean-Chinese who was working with the broker, who confirmed the transfer and handed the phone back. The arrangement gave Lee's sister 70 percent of the money, with a 30 percent cut for the go-betweens.

Smuggled phones, combined with a resourceful underground network of brokers inside and outside North Korea, are allowing defectors not only to connect with long-lost relatives, but to send them desperately needed cash. The process remains risky, both for people within the arm of North Korean law and defectors worried about getting cheated.

The Chinese phones are illegal in North Korea, but cheap and widely available. Since late in the last decade, they have become an increasingly common way for many of the roughly 25,000 defectors in South Korea, and others hiding in China, to talk to and help relatives who stayed behind.

One recent survey by a Seoul civic group of about 400 defectors suggested that one in every two defector families in the South send home money, mostly between 500,000 won ($470) and 3 million won ($2,820) per year. They do this even though most defectors struggle to make a living in the highly competitive, well-educated South: Their average monthly wage is about 1.4 million won ($1,320), about half the pay of an average South Korean worker.

"Even though we have very small incomes here, we still eat rice at every meal," Seoul-based defector Choi Jung-hoon said. "If we don't buy new clothes, we can save some money to send to our family members in the North. That's a lot of money for them."

Reconnecting with family — to talk or send money — is not always simple. Lee said several other brokers failed to connect her with her sister, after she paid them 200,000 won ($190) just for a chance to talk to her.

Under one common method of transferring money, defectors use online banking sites to wire money to a bank account of a Korean-Chinese broker based in a Chinese town near the border with North Korea. The broker then takes out 20 to 30 percent of the money as commissions and asks a Korean-Chinese trader, who can freely cross the border into North Korea, to deliver the rest of the money to the defector's relatives.

The step of carrying money across the border is not always necessary when the go-betweens are involved in separate operations of smuggling Chinese goods for sale in North Korean markets. For example, a North Korean broker who owes money to a Chinese supplier could pay the debt by giving a defector's family cash, if the supplier is also involved in the transaction.

A transfer could require several go-betweens. A defector with no contacts in China may need help from another defector based in South Korea. And if a defector's family lives far from the Chinese border, a transfer will take more effort because North Korea restricts its citizens' movement and has poor transportation services.

Ahn Kyung-su, a South Korean human rights activist who has interviewed many North Korean defectors, said brokers frequently cheated defectors in the early days, but the business has since become more orderly and lucrative, with brokers more concerned about retaining customers.

At the same time, activists and defectors say North Korea has been cracking down, using equipment near the border to check for signals from Chinese mobile phones.

It's not known how many North Koreans have been arrested for getting money from their relatives in South Korea or communicating with them. But activists who have interviewed defectors say many North Koreans have avoided trouble by using some of the money to bribe local officials.

There are additional legal obstacles in South Korea, which restricts citizens' contact with the North but doesn't strictly apply such regulations to defectors.

The money can be a lifeline. South Korea's central bank estimates North Korea's gross national income per capita last year at about 1.4 million won ($1,320). The average South Korean income was 43 times higher. But cash also goes further in the North; analysts say that in rural areas, a house can cost as little as $3,000.

Lee wanted to do more than send cash. Her path to Seoul was long, with a repatriation to the North, an escape from a labor camp and two marriages, one in China and one in South Korea. But she never forgot the people she left behind.

"I miss my family members when I'm free or when I feel lonely. I think about them, forget about them but start thinking about them again," Lee said.

During that phone call in February, she learned that she was not the only one.

"My sister told me she had thought I would have either died or severed contact with her because I was living well somewhere," she said. "I let my husband talk to my sister, and he told her that I've missed and talked about her a lot, and then she cried and cried, saying I didn't forget her."

Lee said the phone talks were arranged after a fellow defector gave her the phone number of a man in North Korea who has an illegal Chinese mobile phone. After several phone talks with Lee, the man located her sister, took her to a border mountain where he could get Chinese mobile signals and called Lee. He immediately rang off to let Lee call back, apparently to save telephone charges.

The broker was supposed to arrange a second telephone conversation to let Lee's sister tell her she got the money. But all he ended up delivering was a voice recording; he said it was of Lee's sister confirming the money transfer, but there was too much static for Lee to tell.

"I told him I could not be sure it was my sister," she said. "But I told him I still appreciated that he arranged for me to talk to her."