Additionally, if you want to keep your region set to USA (this, for example, allows for differentiated notification icons on status bar) and still be able to record calls, you can download a third-party call recording app, since call recording on this phone initially works only when region is set to China.
I use an app called Cube Call Recorder. Besides many other nice settings, it includes a floating widget which appears every time you place or receive a call, so you can record calls on demand, instead of having to use an app that records all your calls, which is annoying and takes a lot of storage space.
You can get the app here:
https://play.google.com/store/apps/details?id=com.catalinagroup.callrecorder