I live in China, so I did a quick test with my coworkers. 4 people. Two phone calls each. Each conversation we dropped the word 'protest' in both English and Chinese. No magical dropped calls for us.
The goverenment is certainly experimenting with such a system in one or two regions, along with their pervasive cameras and face recognition.
However, seeing as the government here seems to have some difficulty building a road on time, on budget, that is actually decent quality it seems unlikely that they'll get this working.