Troubleshoot Call Setup & Media Establishment
This Skill, led by Lalo Nunez, focuses on troubleshooting call setup and media establishment within Cisco Unified Border Element (CUBE) environments. It covers various SIP call flows, including normal call setup and teardown, and scenarios involving SIP responses like 404 Not Found, 487 Request Canceled, and 488 Not Acceptable Media. The Skill also delves into using CLI commands for debugging and verifying media parameters, and addresses common issues with inbound and outbound calls to ITSPs.
Full skill from 300-815 CLACCM. Preview the training IT teams trust.
Updated
Skill 7 of 46 in 300-815 CLACCM
What you'll learn
- Describe a normal SIP call setup and teardown, including INVITE, 100 Trying, 180 Ringing, 200 OK, ACK, and BYE
- Troubleshoot a SIP 404 Not Found with a no matching outgoing dial peer warning by locating and re-enabling a shutdown CUBE dial peer
- Troubleshoot a SIP 408 Request Timeout by correcting the session target IPv4 address on the outbound dial peer from CUBE to CUCM
- Troubleshoot a 480 Temporarily Not Available on outbound ITSP calls by checking CUCM SIP trunk status and OPTIONS ping
- Verify negotiated codecs and local RTP ports on CUBE using show call active voice brief and show voip rtp connections
- Resolve a SIP 488 Not Acceptable Media by changing the dial peer to advertise a codec the ITSP supports
Free 58-minute video lesson with a full transcript and knowledge checks. No account needed to watch.
Introduction
Join Lalo Nunez as he completes Domain 1 of the CLACCM (Implementing Cisco Advanced Call Control and Mobility Services) blueprint. In this introduction video, Lalo discusses the topics we will cover in this Skill.
Normal Call Setup and Tear Down
First, we review a sip call flow with our normal call setup and teardown. Knowing what a successful or normal call setup and teardown should look like will allow us to easily identify when there is an issue with a sip call flow.
Below are the file(s) referenced in the video.
Knowledge Check
An Early Offer is when the media parameters are negotiated within the 200 OK and ACK within an SIP call flow.
404 Not Found
Next, we examine a SIP call flow where we receive a 404 Not Found SIP response.
Below are the file(s) referenced in the video.
Knowledge Check
In this SIP Call Flow why did CUCM send back a response 404 Not Found?
487 Request Canceled
Next, we examine a SIP call flow where we receive a 487 Request Canceled SIP response.
Below are the file(s) referenced in the video. Please note the .txt file(s) contain the output of the debug ccsip messages command.
Knowledge Check
What would cause a CANCEL SIP request to be sent while a call is attempting to be established?
Scenario 1: Incoming calls from the ITSP are not successful
Next, we examine a SIP call flow where we cannot receive inbound calls from the environment.
Below are the file(s) referenced in the video. Please note the .txt file(s) contain the output of the debug ccsip messages command.
Knowledge Check
What header, within the SIP 404 Not Found, did we see the message "No matching outgoing dial-peer"?
Scenario 2: Incoming calls from the ITSP are not successful
Next, we examine another SIP call flow where we cannot receive inbound calls from the environment.
Below are the file(s) referenced in the video. Please note the .txt file(s) contain the output of the debug ccsip messages command.
Knowledge Check
In this demo, what SIP response did we receive when our SIP Request eventually timed out?
Scenario 3: Outbound calls to ITSP are not successful
In our next scenario, we cannot make outbound calls to the ITSP.
Below are the file(s) referenced in the video.
Knowledge Check
What was the "SIP Trunk Status" that CUCM displayed when our SIP Trunk was misconfigured with the wrong port?
Troubleshoot Media Establishment (CLI commands)
In this Nugget, we look at some CLI commands that help us look at the SDP offer/answer between call legs when a call is established.
Please note that I did not review the "debug ccsip messages" command, as we have covered the output of this command in past Skills. Nevertheless, "debug ccsip messages" should be one of the commands you should also be using in your arsenal.
Knowledge Check
Please reference the image above. The output shown is from which command?
Troubleshoot Media Establishment (The approach)
In this Nugget, we look at some factors we can examine when troubleshooting media issues with CUBE.
Knowledge Check
True or False: With Media Flow-Around signaling packets do not terminate on CUBE.
Scenario 4: 488 Not Acceptable Media
Next, we look at a SIP call flow where we receive "488 Not Acceptable Media".
Below are the file(s) referenced in the video. Please note the .txt file(s) contain the output of the debug ccsip messages command.
Knowledge Check
In this demo, what command was used to show us the dial-peers used to set up the call and the negotiated codecs?
Validation
Welcome to the Validation section. We will be “validating” your knowledge through a series of questions. This assessment will gauge your understanding of the content within this Skill. Some of these questions could be associated with visual aids such as images or videos. Watch the Validation video, where we review the answers.
Good luck, and you got this!
Note: Please complete your quiz questions before moving on to the next Skill.
Please refer to the images above to answer the questions below. The output is taken from CUBE for the same active call.
Knowledge Check
Which is the calling number?
Knowledge Check
What is the called number?
Knowledge Check
What port is being used for media by Pedro's endpoint (which has an IP address of 10.0.3.104)?
Knowledge Check
What are the inbound and outbound dial-peers being used?
Knowledge Check
Where do we see which CODEC was negotiated?
Knowledge Check
What is the local port CUBE is using for media for the call between CUBE and Pedro?
Frequently asked questions
What SIP errors does the Troubleshoot Call Setup and Media Establishment lesson walk through?
The lesson works through call flows that return a SIP 404 Not Found with a no matching outgoing dial peer warning, a 408 Request Timeout, a 480 Temporarily Not Available on outbound ITSP calls, and a 488 Not Acceptable Media. Each scenario starts from a review of a normal SIP setup and teardown using INVITE, 100 Trying, 180 Ringing, 200 OK, ACK, and BYE.
How do you fix a SIP 404 no matching outgoing dial peer on CUBE?
In the lesson, the learner uses show call active voice brief to identify which dial peer handles the outbound call leg from CUBE to CUCM, finds that dial peer in a shutdown state, and re-enables it with no shutdown. A test call from the ITSP then rings through as expected.
What causes a 408 Request Timeout or a 480 Temporarily Not Available in a CUBE and CUCM deployment?
The lesson shows a 408 caused by an outbound dial peer from CUBE to CUCM pointing at the wrong address, corrected with the session target ipv4 command. For outbound ITSP calls returning a 480, the learner checks the CUCM SIP trunk to CUBE, where OPTIONS ping acts as a keepalive and the trunk status shows no service.
Which commands verify negotiated codecs and RTP ports on CUBE?
The lesson uses show call active voice brief to confirm the negotiated codec, such as G.711 u-law, and show voip rtp connections to see the local port CUBE uses for media. It also covers asking the right questions, such as whether an issue is reproducible, to narrow down media troubleshooting.
How long is this lesson and how does it fit the 300-815 CLACCM course?
The lesson runs 58 minutes and is one part of the Cisco CCNP Advanced Call Control and Mobility Services (300-815 CLACCM) v1.2 course, which includes more than 35 hours of training. IT Directors and Training Managers can plan the full course as a multi-week enablement path that supports 300-815 CLACCM exam preparation within the CCNP Collaboration certification path.
What should a team member know before taking this troubleshooting lesson?
The course is best assigned to network administrators, collaboration engineers, and voice-focused practitioners with roughly three to five years of Cisco collaboration experience supporting CUCM, CUBE, SIP trunks, and dial peers. The trainer treats the normal call flow segment as review and references dial peer concepts covered elsewhere in the course.
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