Version 5.2 339 September 2007
SIP User's Manual 7. Telephony Capabilities
7 Telephony Capabilities
This section describes the gateway's telephony capabilities.
7.1 Configuring the DTMF Transport Types
You can control the way DTMF digits are transported over the IP network to the remote
endpoint. The following five modes are supported:
îš„ Using INFO message according to the Nortel IETF draft:
In this mode DTMF digits are carried to the remote side within INFO messages.
To enable this mode, define the following:
• RxDTMFOption = 0 (Protocol Management menu > Protocol Definition
submenu > DTMF & Dialing option > 'Declare RFC 2833 in SDP' = No)
• TxDTMFOption = 1 (1
st
to 5
th
DTMF Option = INFO (Nortel))
Note that in this mode, DTMF digits are erased from the audio stream
[DTMFTransportType is automatically set to 0 (DTMF Mute)].
 Using INFO message according to Cisco’s 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 (Cisco))
Note that in this mode, DTMF digits are erased from the audio stream
(DTMFTransportType is automatically set to 0 (DTMF Mute)).
îš„ Using NOTIFY messages according to <draft-mahy-sipping-signaled-digits-01.txt>:
In this mode, DTMF digits are carried to the remote side using NOTIFY messages.
To enable this mode, define the following:
• RxDTMFOption = 0 (Declare RFC 2833 in SDP = No)
• TxDTMFOption = 2 (1
st
to 5
th
DTMF Option = NOTIFY)
Note that in this mode, DTMF digits are erased from the audio stream
(DTMFTransportType is automatically set to 0 (DTMF Mute)).
îš„ 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, define the following:
• TxDTMFOption = 4 (1
st
to 5
th
DTMF Option = RFC 2833)
• RxDTMFOption = 3 (Declare RFC 2833 in SDP = Yes)
Note that 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).
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