Generate DTMF on current channel.
As an example, placing this in the dialplan prior to bridging a call will allow a phone set to rfc2833 OR info to send DTMF tones inband out to the recipient (IVR) or Auto Attendants. Thus changing the outgoing routing from info or rfc2833 to inband.
This option WILL NOT WORK with bridge_early_media when used as so:
- start_dtmf Turn in-band tones into RFC2833