3Com V7122 User Manual page 249

TxDTMFOption = 2
RxDTMFOption = 0
Note that in this mode, DTMF digits are erased from the audio stream
(DTMFTransportType is automatically set to 0 (DTMF Mute)).
Using RFC 2833 relay with Payload type negotiation:
In this mode, DTMF digits are carried to the remote side as part of the RTP stream in
accordance with RFC 2833 standard.
To enable this mode set:
TxDTMFOption = 4
RxDTMFOption = 3
To set the RFC 2833 payload type with a different value (other than its default,
96) configure the 'RFC2833PayloadType' (RFC 2833 Payload Type) parameter.
The gateway negotiates the RFC 2833 payload type using local and remote SDP
and sends packets using the PT from the received SDP. The gateway expects to
receive RFC 2833 packets with the same PT as configured by the
'RFC2833PayloadType' parameter. If the remote side doesn't include 'telephony-
event' in its SDP, the gateway 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 normally used with G.711 coders; with other Low Bit Rate (LBR)
coders the quality of the DTMF digits is reduced.
To set this mode:
TxDTMFOption = 0
RxDTMFOption = 0
DTMFTransportType = 2 ('DTMF Transport Type' = Transparent DTMF)
The gateway is always ready to receive DTMF packets over IP, in all possible
transport modes: INFO messages, NOTIFY, and RFC 2833 (in proper payload
type) or as part of the audio stream.
To exclude RFC 2833 Telephony event parameter from the gateway's SDP, set
RxDTMFOption = 0 in the ini file.
The following parameters affect the way the gateway handles the DTMF digits:
TxDTMFOption and RxDTMFOption (described in
RFC2833PayloadType, MGCPDTMFDetectionPoint, DTMFDigitLength, DTMFVolume,
DTMFInterDigitInterval and DTMFTransportType (described in
V7122 Gateway User Guide
st th
('1 to 5 DTMF Option' = NOTIFY)
('Declare RFC 2833 in SDP' = No)
st th
('1 to 5 Tx DTMF Option' = RFC 2833)
('Declare RFC 2833 in SDP' = Yes)
st th
('1 to 5 Tx DTMF Option' = Disable)
('Declare RFC 2833 in SDP' = No)
Table 41).
T able 46).
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