350-801 Question #274: Real Exam Question with Answer & Explanation

Question

A company's employees have been complaining that they have been unable to select options on the internal IVR of the help desk IT support has been given Cisco UCM traces and below is the snippet of the SDP of the INVITE packet. m=audio 25268 RTP/AVP 18 101 a=rtpmap:0 PCMU/8000 a=rtpmap:18 G729/8000 a=ptime:20 a=fmtp:18 annexb=no a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-15 How is this issue resolved?

Options

• AConfigure CODEC for G.729
• BConfigure DTMF for RFC 2833.
• CConfigure CODEC for G 722
• DConfigure DTMF for KPML

Explanation

The inability to select IVR options despite RFC 2833 support in the SDP suggests a DTMF signaling mismatch or interpretation issue, which can be resolved by configuring the sending device to use an alternative out-of-band DTMF method like KPML.

Common mistakes.

• A. Configuring the CODEC for G.729 relates to voice compression and quality, not the signaling of out-of-band DTMF tones for IVR interaction.
• B. The SDP already indicates that RFC 2833 (telephone-event) is being offered. Reconfiguring for RFC 2833 would not resolve an issue where it is already the method in use but not functioning with the IVR.
• C. Configuring the CODEC for G.722 relates to wideband audio quality and does not affect the signaling of DTMF tones used for IVR interaction.

Concept tested. DTMF signaling methods (RFC 2833, KPML)

Reference. https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/12_5_1/systemConfig/cucm_b_system-configuration-guide-1251/cucm_b_system-configuration-guide-1251_chapter_010.html

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