DTMF Relay Methods
Question
Which DTMF relay method configured on a SIP dial-peer will ensure that a media resource is not invoked by Unified CM for calls to UCCX IVRs?
Answers
Explanations
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A. B. C. D.B.
The correct answer is D. dtmf-relay sip-kpml.
DTMF (Dual Tone Multi-Frequency) is a method of signaling used to transfer the digits or characters from a telephone to the telephone network. SIP (Session Initiation Protocol) is a signaling protocol used for initiating, maintaining, modifying and terminating real-time sessions that involve video, voice, messaging and other communications applications and services between two or more endpoints on IP networks.
When a call is placed to a UCCX (Unified Contact Center Express) IVR (Interactive Voice Response), the DTMF digits entered by the caller need to be transmitted to the IVR system. Depending on how the DTMF digits are transmitted, a media resource may or may not be invoked by Unified CM (Unified Communications Manager).
The four DTMF relay methods listed in the question are:
A. sdtmf-relay h245-signal: This method sends DTMF digits in-band using H.245 signaling. In-band signaling means that the DTMF digits are carried within the same RTP (Real-time Transport Protocol) stream as the audio. This method is not recommended for use with UCCX IVRs because it can result in a media resource being invoked by Unified CM.
B. dtmf-relay rtp-nte: This method sends DTMF digits out-of-band using RTP Named Telephony Events (RTP-NTE). Out-of-band signaling means that the DTMF digits are carried in a separate RTP stream from the audio. This method is not recommended for use with UCCX IVRs because it can result in a media resource being invoked by Unified CM.
C. dtmf-relay sip-notify: This method sends DTMF digits out-of-band using SIP NOTIFY messages. This method is not recommended for use with UCCX IVRs because it can result in a media resource being invoked by Unified CM.
D. dtmf-relay sip-kpml: This method sends DTMF digits out-of-band using SIP KPML (Key Press Markup Language). KPML is an XML-based language that is used to describe the keys or buttons that a user presses. This method is recommended for use with UCCX IVRs because it ensures that a media resource is not invoked by Unified CM.
In summary, the dtmf-relay sip-kpml method is the best option for configuring a SIP dial-peer to ensure that a media resource is not invoked by Unified CM for calls to UCCX IVRs.
