DTMF

A dial tone multi-frequencer (DTMF) it the technical term for the Touch Tone signal used on telephones. It is a standard used to send signals down a twisted pair of wires. In selecting a digital video recorder (dvr) DTMF signals are used by some PTZ type security cameras to send telemetry information to the camera.

This classic technique is particularly useful because it allows the user to simply dial the telephone number of a camera and by simply pressing the buttons on the phone, move the camera.