SIP User's Manual 340 Document #: LTRT-68806
Mediant 2000 & TP-1610 & TP-260/UNI
îš„ Sending DTMF digits (in RTP packets) as part of the audio stream (DTMF Relay is
disabled):
Note that 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 enable this mode, define the following:
• TxDTMFOption = 0 (1
st
to 5
th
DTMF Option = Disable)
• RxDTMFOption = 0 (Declare RFC 2833 in SDP = No)
• DTMFTransportType = 2 (DTMF Transport Type = Transparent DTMF)
îš„ Using INFO message according to Korea mode:
In this mode, DTMF digits are carried to the remote side within INFO messages.
To enable this mode, define the following:
• RxDTMFOption = 0 (Declare RFC 2833 in SDP = No)
• TxDTMFOption = 3 (1st to 5th DTMF Option = INFO (Korea))
• Note that in this mode, DTMF digits are erased from the audio stream
(DTMFTransportType is automatically set to 0 (DTMF Mute)).
Notes:
• 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 to 0 in the ini file.
The following parameters affect the way the SIP gateway handles the DTMF digits:
îš„ TxDTMFOption, RxDTMFOption, and RFC2833PayloadType (described in 'DTMF &
Dialing Parameters' on page 99)
îš„ MGCPDTMFDetectionPoint, DTMFVolume, DTMFTransportType, DTMFDigitLength,
and DTMFInterDigitInterval (refer to 'Channel Parameters' on page 332)
7.2 Fax and Modem Capabilities
7.2.1 Fax/Modem Operating Modes
The gateway supports two modes of operations:
 Fax / modem negotiation isn’t performed during the establishment of the call.
îš„ VBD mode for V.152 implementation (refer to 'Supporting V.152 Implementation' on
page 347): in this mode, fax / modem capabilities are negotiated between the gateway
and the remote endpoint at the establishment of the call. During a call, when a fax /
modem signal is detected, change from voice to VBD (or T.38) is automatically
performed and no additional SIP signaling is required. If negotiation fails (i.e., no
match is achieved for any of the transport capabilities), fallback to existing logic occurs
(according to the parameter IsFaxUsed).
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