The author of the article, Leaving the Witness - a Preacher finds Freedom to Think in Totalitarian China, gives an interesting description of what it was like to be JW missionary in China.
When I got to China, things were really different, by necessity. Pro-selytizing is illegal. Religious meetings are banned. The preaching work and congregation meetings have to be conducted underground. This means that the handful of Witnesses in Shanghai can meet only covertly, which makes seeing each other more than once a week next to impossible. Preaching in the usual structured, door-to-door fashion is also, obviously, out of the question. For me, a Witness accustomed to a life of uniform routine, this seemed like an unprecedented adventure.
A couple of weeks after I arrived in Shanghai, I received a cryptic text message from a man who called himself James (some of us used fake names; we knew the Chinese government monitored electronic correspondence). He proposed meeting in a noisy local restaurant in the French Concession. I called his number when I got to the restaurant and he waved so I would know him. We chatted a few minutes, then he immediately got down to business. With a practiced manner, he explained the instructions from the branch office of Jehovah’s Witnesses as to how to conduct my missionary work. I was to find a job, perhaps teaching English, as a cover. Then I was to start cultivating relationships with worldly people, both Chinese and Westerners. These friendships were to be made with the sole purpose of religious conversion.