How can a mobile phone prevent others from making calls? Who has that directive?

You can try to enter **21*888888# and press the dial button to turn on the call transfer function of this machine. After it is turned on, others calling you will be forwarded to the empty number 888888 to achieve other functions. The effect of the call being unable to come in. The following is an introduction to the relevant steps:

1. Just enter **21*888888# on the dialing interface of the Android or Apple iOS 11 mobile phone, and then press Dial to activate call transfer. 888888 is the forwarded number. Since this number is empty, others cannot call your mobile phone;

2. The method of unblocking is also simple, just dial ##21# and then dial again. Disable access to receive calls again.