How to turn it off if you are busy?

First, in the mobile phone, find "Settings" and enter.

2.

Then find "Flight Mode" in the phone settings and turn it on.

3.

Or you can enter the setting interface of wireless network (WIFI) and switch the WIFI switch back and forth, with an interval of about 2S, which artificially causes unstable network connection.

4.

In this way, the other party will receive a prompt that "the other party is busy".