/kloc-Call failed after 0/0 seconds.

This is a signal problem. Generally, I turn off 3G and wifi when I make a phone call, and then call again, because sometimes the network will switch when you make a phone call, which will affect your call quality. After all, the call is in a 2G network, and this will happen if 3G coverage is not comprehensive. It also has something to do with the venue. The signal in the elevator, toilet or stairwell on the floor is not very good. I suggest you turn off the network next time you make a phone call.

Generally speaking, making a phone call is an act of dialing with the phone key and talking to the other party after being connected. Principle of calling: DTMF (early pulse dialing) is the basic dialing method currently used. Dual-tone multi-frequency refers to DTMF (Dual-tone multi-frequency), and DTMF signals are composed of eight frequencies. These eight frequencies are divided into two groups: low frequency group and high frequency group. Conversation is a kind of communication technology that uses electricity as the medium and transmits language through the mutual conversion of acoustic energy and electric energy. When the "calling party" picks up the phone and speaks into the microphone, the vibration of the vocal cords excites the air to vibrate, forming sound waves. Sound waves act on the microphone to generate current, which is called speech current. The voice current is transmitted to the program-controlled exchange along the line, and the program-controlled exchange transmits the voice signal to the receiver of the "called party" phone, which plays the opposite role to the microphone-converting the current into sound waves and transmitting them to people's ears through the air. The simplest call process is completed. In a word, the easiest way for two users to talk is to connect two phones with a pair of wires. When the "calling party" sends the DTMF signal dialed off-hook to the program-controlled exchange of this bureau through the telephone line. Through the program-controlled exchange and then through the telephone line to the phone, the two sides can talk!