Exam 350-801 topic 1 question 105 discussion

Answer is B. "A transcoder takes the media stream of one codec and transcodes (converts) it from one compression type to another compression type. For example, it could take a stream from a G.711 codec and transcode (convert) it in real time to a G.729 stream. In addition to codec conversion, a transcoder resource can also provide MTP/TRP functionality to a call."

Answer B D. Nothing: both sides support payload type 101: Payload type 101 refers to DTMF events, not the actual audio codec

Correct answer is B.

101 is "telephone-event" --> DTMF

Correct answer is B.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/dtmf-relay.html i think the reason it allows SUBSCRIBE/NOTIFY is because it allows kpml. subscribe is just the initial registration of the NOTIFY out-of-band method. the actual keys are transmitted in the NOTIFY then: sip-kpml —This method is available only on SIP dial peers. The RFC 4730 defines the out-of-band DTMF relay mechanism to register the DTMF signals using the SIP-Subscribe messages. It transports the DTMF signals using the SIP-Notify messages containing an XML-encoded body. This method is calked Key Press Markup Language. If you configure KPML on the dial peer, the gateway sends INVITE messages with KPML in the Allow-Events header. NOTIFY sip:192.168.105.25:5060 SIP/2.0 Event: kpml <?xml version="1.0" encoding="UTF-8"?>

The answer is B. The invite come with PCMU/8000, and not see G729/8000... transcoding is need it.

Lol D is not the answer. The invite is offered with only g711. If the invited endpoint only support g729, how can one think the answer is D? The answer is B.

B is correct, transcoder is needed for translating

D is correct as the call would be negotiated with G729

A call can be proceed without audio support so payload 101 is suffisent.

I meant should be B.

Should be C. Sender supports G.711u only. Tranccoder is needed.