The canInsertDTMF attribute must indicate if the RTCDTMFSender is capable of sending DTMF.
The duration attribute must return the current tone duration value.
An RTCDTMFSender object's insertDTMF() method is used to send DTMF tones.
The interToneGap attribute must return the current value of the between-tone gap.
This event handler uses the RTCDTMFToneChangeEvent interface to return the character for each tone as it is played out.
The toneBuffer attribute must return a list of the tones remaining to be played out.
The track attribute must return the MediaStreamTrack given as argument to the createDTMFSender() method.