350-801 Question #480: Real Exam Question with Answer & Explanation

The correct answer is B: dtmf-relay rtp-nte. This question asks to identify the DTMF relay method that uses in-band signaling for user keypresses in a Cisco collaboration environment. The dtmf-relay rtp-nte command configures the system to send DTMF tones as RTP Named Telephone Events (NTE), which is a form of in-band signa

Voice Gateways and Session Border Controllers

Question

Cisco UCM users with Cisco 8800 series IP telephones require access to a DTMF-based IVR solution. The IVR is connected via SIP through a Cisco Unified Border Element. Which configuration uses in-band signaling for the users' keypresses?

Options

Adtmf-relay sip-kpml
Bdtmf-relay rtp-nte
Cdtmf-relay sip-notify
Ddtmf-relay sip-inband

Explanation

This question asks to identify the DTMF relay method that uses in-band signaling for user keypresses in a Cisco collaboration environment. The dtmf-relay rtp-nte command configures the system to send DTMF tones as RTP Named Telephone Events (NTE), which is a form of in-band signaling.

Common mistakes.

A. dtmf-relay sip-kpml is an out-of-band DTMF relay method where key presses are sent as XML messages within SIP INFO packets, not within the media stream.
C. dtmf-relay sip-notify is an out-of-band DTMF relay method, similar to SIP INFO, where DTMF digits are sent in SIP NOTIFY messages, separate from the media stream.
D. dtmf-relay sip-inband is not a valid or standard DTMF relay command; true in-band DTMF implies the tones are mixed with the audio and rely on the codec to pass them, or using RTP-NTE for signaling within the media path.

Concept tested. DTMF Relay Methods in SIP/RTP

Reference. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/dtmf_rfc2833_kpml_notify.html

Topics

#DTMF Relay#Cisco CUBE#SIP#RTP

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