Chinese SIM purchase at CAN
 

I have a long stopover in Guangzhou and want to look around the city. I don’t have a Chinese phone number, so getting access to wifi is nigh on impossible (since they have to send a code by text). I want to purchase a Chinese SIM just for 24 hours...I really only need data and don’t really care what I pay (I realise things are always more expensive at airports). I know where the counter is to do this. My question is...can anyone CONFIRM whether it is required to return the SIM in leaving the country? I will be paying in cash. But I don’t want to be prevented from doing this each time I go through China. Please reply IF YOU KNOW FOR CERTAIN.

I bought a unicom SIM for visiting family members (y56 for 100 minutes voice and 500 mb data) yesterday. The notion of returning it never came up. I just won't add any more money to it after they leave and let it expire.