RTCDTMFToneChangeEvent

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2020.

TheRTCDTMFToneChangeEvent interface represents events sent to indicate thatDTMF tones have started or finished playing. This interface is used by thetonechange event.

Instance properties

In addition to the properties ofEvent, this interface offers the following:

RTCDTMFToneChangeEvent.toneRead only: A string specifying the tone which has begun playing, or an empty string ("") if the previous tone has finished playing.

Constructors

RTCDTMFToneChangeEvent(): Returns a newRTCDTMFToneChangeEvent. It takes two parameters, the first being a string representing the type of the event (always"tonechange"); the second a dictionary containing the initial state of the properties of the event.

Instance methods

Supports the methods defined inEvent. There are no additional methods.

This snippet is derived loosely from the full, working example you'll find in the section onWhen a tone finishes playing. It appends each tone to a display box as it's played, and, once all tones have been sent, re-enabled a previously-disabled "Send" button, allowing the next DTMF string to be entered.

dtmfSender.addEventListener("change", (event) => {  if (event.tone !== "") {    dialStringBox.innerText += event.tone;  } else {    sendDTMFButton.disabled = false;  }});