Yealink VC880 - Transmission Ways of DTMF; Setting DTMF Transmission Method for SIP Protocol

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Transmission Ways of DTMF
Three ways to transmit DTMF tones are as below: RFC2833, INBAND, SIP INFO.
RFC 2833
In-band transmission method. DTMF tones are transmitted by RTP, and the RFC 2833 packets are marked
by TeleponeEvent (RTP PayloadType). One DTMF tone consists of several RTP packets with the same
timestamps, which can be used to identify the same key. If the End bit of a RTP packet is 1, the packet is the
last DTMF tone. The default telephoneEvent is 101, and you can change it.
INBAND
In-band transmission method. DTMF tones are transmitted together with the voice band. By analyzing the
high frequency and the low frequency of the RTP packets, the device can identify the corresponding key.
SIP INFO
Out-band transmission method. DTMF tones are transmitted by SIP signaling path. The SIP INFO message
can transmit DTMF tones in three ways: DTMF, DTMF-Relay and Telephone-Event.
Setting DTMF Transmission Method for SIP Protocol
You can set the DTMF transmission method for the SIP protocol when using a SIP account, SIP IP call, or
logging in to Zoom, Pexip, BlueJeans, EasyMeet, or a custom third-party platform.
Procedure
1. Do one of the following:
• On your web user interface, go to Account > SIP Account/SIP IP Call.
• On your web user interface, go to Account > VC Platform > Video Conference Platform >
Platform Type > Zoom/Pexip/BlueJeans/EasyMeet/Custom.
• On your VCS, go to More > Setting > Advanced > SIP IP Call Out.
On your VP59, tap Setting > Advanced > SIP IP Call.
• On your CTP20, tap Setting > Advanced > SIP IP Call Out.
2. Configure and save the following settings:
Parameter Description Configuration Method
DTMF Type
Configure the DTMF type.
• INBAND—DTMF digits are transmitted
in the voice band, together with the
general RTP voice packet.
• RFC2833—DTMF digits are transmitted
by RTP packet which is compliant to
RFC2833.
• SIP INFO—DTMF digits are transmitted
by SIP INFO.
• RFC2833+ SIP INFO—DTMF digits are
transmitted by RFC 2833 and the SIP
INFO.
Default: RFC2833.
Web user interface
Endpoint
CTP20