What do I need to know about phones in China?

IOS? Android?  Do they both work in China?

Most smart phones work perfectly fine in China regardless if they are IOS or Android.

How will it work for changing over to a Chinese SIM?

Usually it is just a matter of getting a new phone plan/Chinese SIM card and then popping out your old SIM and putting in the new one.
When it comes to phone usage plans China is almost always cheaper, especially when compared to any international plan.
Usually everyone is surprised just how cheap the data/phone plans are in China.

Locked/Unlocked?

Make sure your phone is unlocked. I think it is law now that carriers cannot lock your phone but if your phone was locked years ago and you never asked them to unlock it, then it may be locked.  If your phone is locked, then you cannot use a Chinese SIM (so either need to get a new phone or have to take care of getting your phone unlocked from here which can be more difficult). Apple users seems to be able to use their unlocked phones much easier. Android users sometimes find it easiest to buy a new phone in China (you can get a half decent one for around 120 USD).

WIFI Packages

For the arrival process, usually the wifi for your apartment and the Chinese SIM card come as a package. Some teachers are able to arrive and get straight into an apartment.

E-SIM

The airport and hotel will normally have wifi, but having the piece of mind of just being connected when you arrive or when you explore is probably worth having either a China SIM or E-SIM. If you are training in a difference city it is probably a must. If you are arriving in the city you will be teaching in, we will try to get your WIFI and phone plan set up for you quickly but it still might advised to have the comfort of a being connected.

For Esims, Airalo seems to be one of the biggest providers. Here is a link to their site: https://www.airalo.com/china-esim

Once you buy a Esim it will take you through step-by-step on how to set it up on your phone.

If you have a fairly new phone it should be able to take an e-sim. This is like adding a sim card but without actually using another physical card. It also allows you to use two numbers (or having the control to switch between them as you like).

Physical SIM

If your phone cannot take esims, then you may want a physical sim card that you can switch with your current sim.

Here is an option:
https://www.simoptions.com/prepaid-sim-card-china/
Sometimes it is also possible to get an overseas package added to your current phone plan as well that you can use until you get the new China SIM.

How long do I need it to last for?  How much data?

A week should be fine. It will normally be cheaper to get a real sim and change over to a Chinese number after you arrive and this should be all ready within your first week.

For Data, it really depends on you.  You probably wont need to much, but I personally got 1GB in the past and clicked on a download without thinking and used up the full GB, so maybe a little more than that might be nice.