Passport? Good.

China

Phone and internet

Getting a number, and which of your usual apps will not open.

Diagram: a SIM in China is registered against your passport at the point of sale

Can I use my own phone in China?

Yes, but decide how before you fly. A local SIM has to be registered against your passport, and a number of services you use daily will not load.

Ministry of Industry and Information Technology

Sort the practical stuff before you fly.

eSIMs, rail passes, and airport transfers — the things worth booking before you land.