2.2 Troubleshoot Elements of a SIP 350-801 Practice Questions (Page 2)

Questions 6–10

1. 6foundation · easy

   A SIP endpoint sends a BYE message but receives no response from the remote party. What is the most likely abnormal teardown scenario?

   • AThe BYE message was sent before the INVITE was acknowledged.
   • BThe remote party is waiting for a CANCEL message.
   • CThe BYE message was sent with an incorrect Call-ID.
   • DThe remote party has already terminated the session and is no longer responding.
   Reveal Solution Discussion Select an answer first
2. 7application · medium

   A Cisco IP phone and a softphone are on the same LAN. The phone offers `m=audio 4000 RTP/AVP 0 8 18` and `m=video 4002 RTP/AVP 96`. The softphone answers with `m=audio 5000 RTP/AVP 0` and `m=video 0 RTP/AVP 96`. The call connects with audio, but video does not work. What is the most likely reason?

   • AThe phone offered H.264 (payload type 96), but the softphone only supports H.263.
   • BThe softphone rejected the video stream by setting the port to zero in the SDP answer.
   • CThe softphone's answer omitted the `a=rtpmap` for payload type 96, so the codec could not be used.
   • DThe phone did not include `a=sendrecv` for the video stream, so the softphone set it to `inactive`.
   Reveal Solution Discussion Select an answer first
4. 8foundation · easy

   Which SDP line indicates the media type (e.g., audio or video), the transport port, and the list of supported payload types?

   • Am= line
   • Bo= line
   • Ca= line
   • Dc= line
   Reveal Solution Discussion Select an answer first
5. 9foundation · easy

   After a call is resumed from hold, which SDP attribute should be present in the re-INVITE to indicate that both endpoints can send and receive media?

   • Aa=sendonly
   • Ba=sendrecv
   • Ca=inactive
   • Da=recvonly
   Reveal Solution Discussion Select an answer first
6. 10application · medium

   A user reports that when they press DTMF digits during a call to an IVR, the IVR does not respond. The SIP trace shows the SDP offer from the user's phone contains `m=audio 4000 RTP/AVP 0 8 101` and `a=rtpmap:101 telephone-event/8000`. The IVR's 200 OK answer contains `m=audio 5000 RTP/AVP 0 8` but no telephone-event line. What is the most likely cause of the DTMF failure?

   • AThe user's phone is sending DTMF as in-band audio, which the IVR cannot detect.
   • BThe user's phone used the wrong event code for DTMF digits in the RTP stream.
   • CThe IVR selected G.711 a-law (payload type 8), which does not support DTMF transmission.
   • DThe IVR did not include payload type 101 in its answer, so it will not accept RFC 2833 DTMF events.
   Reveal Solution Discussion Select an answer first