Configuring Dtmf Transport Types - AudioCodes Mediant 800B User Manual

Note: This feature is applicable only to the Gateway application.

14.3.3 Configuring DTMF Transport Types

The device supports various methods for transporting DTMF digits over the IP network to
the remote endpoint. The methods and their configuration can be configured in the DTMF
& Dialing page (Configuration tab > VoIP menu > Gateway > DTMF and Supplementary
> DTMF & Dialing):
Figure 14-5: DTMF Transport Parameters in Web Interface

Using INFO message according to Nortel IETF draft: DTMF digits are sent to the
remote side in INFO messages. To enable the mode:
a. Set the 'Declare RFC 2833 in SDP' parameter to No (RxDTMFOption = 0).
b. Set the 'First Tx DTMF Option' parameter to INFO Nortel (FirstTxDTMFOption =
1).
Note: DTMF digits are removed from the audio stream (and the 'DTMF Transport
Type' parameter is automatically set to Mute DTMF).

Using INFO message according to Cisco's mode: DTMF digits are sent to the
remote side in INFO messages. To enable the mode:
a. Set the 'Declare RFC 2833 in SDP' parameter to No (RxDTMFOption = 0).
b. Set the 'First Tx DTMF Option' parameter to INFO Cisco (FirstTxDTMFOption =
3).
Note: DTMF digits are removed from the audio stream (and the 'DTMF Transport
Type' parameter is automatically set to Mute DTMF).

Using NOTIFY messages according to IETF Internet-Draft draft-mahy-sipping-
signaled-digits-01: DTMF digits are sent to the remote side using NOTIFY
messages. To enable the mode:
a. Set the 'Declare RFC 2833 in SDP' parameter to No (RxDTMFOption = 0).
b. Set the 'First Tx DTMF Option' parameter to NOTIFY (FirstTxDTMFOption = 2).
Note: DTMF digits are removed from the audio stream (and the 'DTMF Transport
Type' parameter is automatically set to Mute DTMF).

Using RFC 2833 relay with Payload type negotiation: DTMF digits are sent to the
remote side as part of the RTP stream according to RFC 2833. To enable the mode:
a. Set the 'Declare RFC 2833 in SDP' parameter to Yes (RxDTMFOption = 3).
b. Set the 'First Tx DTMF Option' parameter to RFC 2833 (FirstTxDTMFOption = 4).
Note: To set the RFC 2833 payload type with a value other than its default, use the
RFC2833PayloadType parameter. The device negotiates the RFC 2833 payload type
using local and remote SDP and sends packets using the payload type from the
received SDP. The device expects to receive RFC 2833 packets with the same
payload type as configured by the parameter. If the remote side doesn't include
'telephony-event' in its SDP, the device sends DTMF digits in transparent mode (as
part of the voice stream).

Sending DTMF digits (in RTP packets) as part of the audio stream (DTMF Relay
is disabled): This method is typically used with G.711 coders. With other low-bit rate
(LBR) coders, the quality of the DTMF digits is reduced. To enable the mode:
User's Manual
Mediant 800B Gateway and E- SBC
196 Document #: LTRT-10296