SIP DTMF Support
SIP gateways can use Cisco proprietary NOTIFY-based out-of-band DTMF relay. In addition,
NOTIFY-based out-of-band DTMF broadcast can additionally be acclimated by analog phones
attached to analog articulation ports on the router.
NOTIFY-based out-of-band DTMF broadcast sends letters bidirectionally amid the
originating and absolute gateways for a DTMF accident during a call. If assorted DTMF
relay mechanisms are enabled on a SIP punch associate and are adjourned successfully,
NOTIFY-based out-of-band DTMF broadcast takes precedence.
The basic aperture sends an Invite bulletin with SIP Call-Info attack to announce the
use of the NOTIFY-based out-of-band DTMF relay. The absolute aperture acknowledges
the bulletin with an 18x or 200 Acknowledgment message, additionally application the Call-Info header.
Whenever a DTMF accident occurs, the aperture sends a SIP NOTIFY bulletin for that
event afterwards the SIP Invite and 18x or 200 Acknowledgment letters accommodate the NOTIFYbased
out-of-band DTMF broadcast mechanism. In response, the aperture expects to accept a
200 OK message. The NOTIFY-based out-of-band DTMF broadcast apparatus is agnate to
the DTMF bulletin architecture declared in RFC 2833.