Join us at SIPNOC 2017 November 28-30, 2017 and attend our intensive training workshop, “Wireshark for VoIP Ninjas!” 🥋

School of VoIP VoIP Call Control & Troubleshooting

This course is intended for VoIP network engineers and operators to understand advanced issues in IP Networking, VoIP Signaling and Media, and Troubleshooting practice.


This course is intended for VoIP network engineers and operators to understand advanced issues in IP Networking, VoIP Signaling and Media, and Troubleshooting practice.

At the end of the course, you will be able to:

Course Content

VoIP Basics & Components. These modules introduces VoIP systems, including call flows, SIP, and MGCP. The VoIP Components module introduces VoIP Customer Premise Equipment, SIP Servers / Call Agents, Redirect servers, MGCP gateways and Session Border Controllers and how they interact with each other, and other network components. Participants will learn how to intelligently plan deployments cognizant of protocol interactions. Exercises ensure participants have a good understanding of the different roles.

Session Border Controllers. Session Border Controllers play a key role in providing security an enabling the use of NAT in VoIP services. They are, however, complicated devices, and often not understood. In this module, participants learn about how the SBC can enable NAT traversal, SIP peering, and provide a security barrier between untrusted networks and the VoIP core. In exercises, participants monitor and simulate the exact function of an SBC on SIP signaling.

VoIP Media. Unlike TDM networks, IP networks can drop, re-order, and delay data as it is transmitted. Reliable transmission of toll-grade audio across such networks requires careful consideration of the underlying structure of the signal and its encoding. This section covers digital audio encoding, packetization into RTP, the effects of IP networks on RTP, jitter buffer operation, and the effects of prioritization and congestion on real-time streams. In exercises, students enable prioritization on routers and test the effects.

SIP & MGCP Operation. These modules provides a working understanding of SIP and MGCP processing, and introduce the key facts needed to understand and troubleshoot problems in SIP and MGCP networks. Coverage is given to the differences between the protocols. Participants have opportunities to read and troubleshoot call traces.

VoIP Network Troubleshooting Process. Troubleshooting is approached in this module as a first-class enterprise, required in every complex system. This module introduces a consistent process for identifying problems that encourages confidence, preparedness, and careful analysis of component behavior.

Effective Mental Models for VoIP Troubleshooting. A key to effective troubleshooting is reasonable comprehension of the system; this module shows ways to develop coherent depictions of VoIP networks to help quickly isolate faults and plan changes. We cover a variety of diagram formats to describe networks. Participants have opportunities to develop diagrams of their own networks that clearly identify certain functionality in the context of network layers and signaling design.

Experimental Troubleshooting by Testing Components. To find problems, you must know which components are not the problem. This module shows techniques for testing components with the aim of identifying problems.

Common Problems Encountered in VoIP Networks. This module is about isolating some of the common issues that affect VoIP networks. The problem types cover audio quality, faxing, signaling, and registration. Here we show the effects of these problems, and how to isolate the root causes.


Participants should either complete the IP Foundations for VoIP Carriers, or else have the Cisco Certified Network Professional (CCNP) certification and familiarity with VoIP systems.

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