DTMF stands for "Dual-Tone Multi-Frequency." It is a telecommunication signalling feature used in a VoIP (Voice over Internet Protocol) system. "In-band" signalling is the process of sending metadata and control information within the same band and on the same channel. When you dial a number, it is encoded and transmitted across a telephone line as Dual-Tone Multi-Frequency (DTMF) tones. As an administrator, you can test your DTMF on an Asterisk server using the "Dial" command.
Log in to an Asterisk server using administrative credentials.
Double-click to open a "Command prompt" or "Terminal window" (depending on your system) from the desktop.
Type the following without the quotes:
Press the "Enter" key. Replace "