Web/API/RTCDTMFSender/toneBuffer

The RTCDTMFSender interface's toneBuffer property returns a string containing a list of the DTMF tones currently queued for sending to the remote peer over the RTCPeerConnection. To place tones into the buffer, call insertDTMF().

Tones are removed from the string as they're played, so only upcoming tones are listed.

Syntax

var toneBuffer = RTCDTMFSender.toneBuffer;

Value

A DOMString listing the tones to be played. If the string is empty, there are no tones pending.

Tone buffer format

The tone buffer is a string which can contain any combination of the characters that are permitted by the DTMF standard.

DTMF tone characters

The digits 0-9: These characters represent the digit keys on a telephone keypad.
The letters A-D: These characters represent the "A" through "D" keys which are part of the DTMF standard but not included on most telephones. These are not interpreted as digits. Lower-case "a"-"d" automatically gets converted to upper-case.
The pound/hash sign ("#") and the asterisk ("*"): These correspond to the similarly-labeled keys which are typically on the bottom row of the telephone keypad.
The comma (","): This character instructs the dialing process to pause for two seconds before sending the next character in the buffer.

All other characters are unrecognized and will cause insertDTMF() to throw an InvalidCharacterError exception.

Using tone buffer strings

For example, if you're writing code to control a voicemail system by sending DTMF codes, you might use a string such as "*,1,5555". In this example, we would send "*" to request access to the VM system, then, after a pause, send a "1" to start playback of voicemail messages, then after a pause, dial "5555" as a PIN number to open the messages.

Settting the tone buffer to an empty string ("") cancels any pending DTMF codes.

Example

tbd

Specifications

Specification	Status	Comment
WebRTC 1.0: Real-time Communication Between BrowsersThe definition of 'RTCDTMFSender.toneBuffer' in that specification.	Candidate Recommendation

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`toneBuffer`	Chrome Full support 27	Edge Full support ≤79	Firefox Full support 52	IE No support No	Opera Full support Yes	Safari ?	WebView Android Full support 4.4	Chrome Android Full support 27	Firefox Android Full support 52	Opera Android Full support Yes	Safari iOS ?	Samsung Internet Android Full support 1.5

Legend

Full support: Full support
No support: No support
Compatibility unknown: Compatibility unknown