RTCDTMFSender: toneBuffer property

{{APIRef("WebRTC")}}

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

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

Value

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

Exceptions

• InvalidCharacterError {{domxref("DOMException")}}
  • : Thrown if a character is not a DTMF tone character (0-9, A-D, #, or ,).

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.

[!NOTE] All other characters are unrecognized and will cause {{domxref("RTCDTMFSender.insertDTMF", "insertDTMF()")}} to throw an InvalidCharacterError {{domxref("DOMException")}}.

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.

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

Example

tbd

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• WebRTC API
• Using DTMF with WebRTC
• {{domxref("RTCDTMFSender.insertDTMF()")}}
• {{domxref("RTCPeerConnection")}}
• {{domxref("RTCDTMFSender")}}
• {{domxref("RTCRtpSender")}}