350-801 Question #446: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. An INVITE with the SDP in the exhibit is received. Based on the configuration, which two codecs will be in the SDP of the outbound INVITE? (Choose two.)

Options

• AG.729r8
• Bisac
• Cilbc
• DG.711ulaw
• EG.7l1alaw

Explanation

The outbound INVITE SDP will include G.711ulaw and iLBC because these codecs are typically configured as preferred or allowed on Cisco voice devices and were likely offered by the incoming INVITE and matched by the system's capabilities.

Common mistakes.

• A. G.729r8 is a low-bandwidth codec, but it might not be chosen if higher-quality options like G.711ulaw or specific error-resilient codecs like iLBC are preferred by configuration or available bandwidth.
• B. ISAC (Internet Speech Audio Codec) is a wideband audio codec developed by Google, which is not a standard codec often prioritized by default in Cisco's traditional telephony environments for general calls.
• E. G.711alaw is an alternative to G.711ulaw primarily used in Europe and other regions, so if the system is configured for ulaw, alaw would not be chosen for a North American or similarly configured system.

Concept tested. SIP codec negotiation and preference

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_0100.html#concept_F9F7E80332205562095C089874B20F2B

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