I want to use an unlimited SIM card in China (Shanghai if the city is relevant). There are some SIM cards available in China (e.g. China Unicom and China Mobile) but I only know SIM cards that have a fixed amount of data to consume.
Since the unlimited data is the top priority, I don't mind if it has the phone number or can be used as a tethering, though both of them would be great if at all possible. I don't mind at all if it is 4G/LTE, though.
Of course I must purchase it as a traveler, who doesn't have an official proof of residence. Can I still purchase it in China?