User`s manual

SIP User's Manual 8. Telephony Capabilities
Version 5.0 209 October 2006
4. 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 ('1
st
to 5
th
Tx 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).
5. 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 set this mode:
• TxDTMFOption = 0 ('1
st
to 5
th
Tx DTMF Option' = Disable)
• RxDTMFOption = 0 ('Declare RFC 2833 in SDP' = No)
• DTMFTransportType = 2 ('DTMF Transport Type' = Transparent DTMF)
Note 1: 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.
Note 2: 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 Table 6-7).
 RFC2833PayloadType, MGCPDTMFDetectionPoint, DTMFDigitLength,
DTMFVolume, DTMFInterDigitInterval and DTMFTransportType (described in Table
6-12).