RTCRtpSender interface provides the ability to control and obtain details about how a particular
MediaStreamTrack is encoded and sent to a remote peer.
RTCDTMFSender which can be used to send
DTMF tones using
"telephone-event" payloads on the RTP session represented by the
RTCRtpSender object. If
null, the track and/or the connection doesn't support DTMF. Only audio tracks can support DTMF.