Media5 Mediatrix 4104, Справочное руководство

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DTMF Transport Type Reference Manual (SIP Version)
Mediatrix 4104 235
DTMF Transport Type
You can define how to transport the DTMFs.

To set the DTMF transport type:
1. In the voiceIfMIB, set the DTMF transport type in the voiceIfDtmfTransport variable
( voiceIfDtmfTransportTable group).
The following choices are available:
Note:
The packetization time is not negotiated between endpoints, so a minimum and a maximum don't
make much sense. The selected value is the default RTP value (20 ms for G.711, G.726, and G.729.AB) if
it is included in the range delimited by the minimum and maximum. Otherwise, it is the minimum.
Standards Supported • draft-choudhuri-sip-info-digit-00.txt
• ITU-T Recommendation Q.24 : Multifrequency push-button
signal reception
• RFC 2833: RTP Payload for DTMF Digits, Telephony Tones
and Telephony Signals
DTMF out-of-band
Certain compression codecs such as G.723.1 and G.729 effectively distort voice because they lose
information from the incoming voice stream during the compression and decompression phases. For
normal speech this is insignificant and becomes unimportant. In the case of pure tones (such as DTMF)
this distortion means the receiver may no longer recognize the tones. The solution is to send this
information as a separate packet to the other endpoint, which then plays the DTMF sequence back by re-
generating the true tones. Such a mechanism is known as out-of-band DTMF. The Mediatrix 4104
receives and sends out-of-band DTMFs as per ITU Q.24. DTMFs supported are 0-9, A-D, *, #.
Table 149: DTMF Transport Type Parameters
Transport Parameter Description
inBand The DTMFs are transmitted like the voice in the RTP
stream.
outOfBandUsingRtp The DTMFs are transmitted as per RFC 2833 (see “DTMF
Payload Type” on page 236 for additional information).
outOfBandUsingSignalingProtocol The DTMFs are transmitted as per draft-choudhuri-sip-info-
digit-00.txt (see “DTMF Transport Using SIP INFO” on
page 236 and “DTMF Transport over the SIP Protocol” on
page 237 for more details).
Note : This feature and the Hook Flash processing feature
via signalling protocol are totally independent. Activating
one of these features has no effect on the other. See
“Hook
Flash Processing” on page 322 for more details.
signalingProtocolDependent The signalling protocol has the control to select the DTMF
transport mode. The SDP body includes both RFC 2833
and
draft-choudhuri-sip-info-digit-00.txt in that order of
preference.