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.