The name property. Must have the value sendDtmf.
OptionalvalueA string that determines the DTMF tones to play to the callee when the call is picked up. Valid characters are: 0-9, #, and w. w renders a 500ms pause. For example, the string ww1234#w#, plays a 1 second pause, the DTMF tones for 1, 2, 3, 4, and #, followed by a 500ms pause and finally the # tone. This is useful if the callout destination requires a conference PIN code or an extension. If there is a calling party, it will hear progress while the DTMF is sent.
Plays DTMF tones in the call.