Yealink SIP-T2 SERIES Administrator's Manual page 479

SIP INFO
DTMF digits are transmitted by the SIP INFO messages when the voice stream is
established after a successful SIP 200 OK-ACK message sequence. The SIP INFO
message is sent along the signaling path of the call. The SIP INFO message can transmit
DTMF digits in three ways: DTMF , DTMF-Relay and Telephone-Event.
Procedure
Configuration changes can be performed using the configuration files or locally.
Configuration File
<MAC>.cfg
<y0000000000xx>.cfg
Configuring Basic Features
Configure the method of
transmitting DTMF digit and the
payload type on per-line basis.
Parameters:
account.X.dtmf.type
account.X.dtmf.dtmf_payload
account.X.dtmf.info_type
Configure the method of
transmitting DTMF digit and the
payload type for IP call.
Parameters:
account.17.dtmf.type
account.17.dtmf.dtmf_payload
account.17.dtmf.info_type
Configure the number of times
for the IP phone to send the end
RTP Event packet.
Parameter:
features.dtmf.repetition
Configure the duration time for
DTMF .
Parameter:
features.dtmf.duration
Configure the frequency level
of DTMF digits.
Parameter:
features.dtmf.volume
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