The call read-only property of the CallEvent interface returns a TelephonyCall object indicating the call from which the event originated.
The sendTones() method of the Telephony Interface generates multiple DTMF tones, with a specified duration for each tone, and an optional delay before generation starts. The tones are sent to the currently active call.
The startTone() method of the Telephony Interface begins generating the tone for the specified DTMF character. The tone is sent to the currently active call, and continues to sound until a corresponding call to Telephony.stopTone().