Book: Troubleshooting Cisco IP Telephony

Terry Slattery
Principal Architect

The Cisco Press book Troubleshooting Cisco IP Telephony is a gem.  I spoke on troubleshooting VoIP in converged networks at VoiceCon this week (see the prior post) and some of the ideas for problems came from this book. It is easy to read and is organized in a way that also allows it to be used as a reference when you’re encountering a problem and would like some troubleshooting ideas.  At 973 pages, it might be intimidating, but I found it easy to use.  There is a two-page quick index of major topics on the inside front cover where it is easy to find.  I wish more books did that.  A full index is in the end as well, if you don’t find the topic you’re seeking in the quick index.

The first few chapters explain IP Telephony architecture, troubleshooting methodology, and troubleshooting tools. The next chapters cover  phone registration and various hardware like phones and gateways.  If you’re looking for ideas on troubleshooting a voip problem, you’ll want to read through the chapters on voice quality, call routing, call preservation, transcoding, and conference bridges.  These chapters are the core of the operation of voip and a good understanding of what can go wrong is important when you’re troubleshooting.  Next, you’ll find information about music-on-hold, call admission control, voicemail, and survivable remote site telephony (SRST, useful when your branch connection to the central call controller goes out).  Finally, there are chapters on things that aren’t strictly voip, but are important to understand: applications, database replication, and LDAP integration.

I found the writing style to be very conversational, making it easy to read and understand.   If you’re working on voip or your organization is thinking about it, I highly recommend getting a copy.



Re-posted with Permission 

NetCraftsmen would like to acknowledge Infoblox for their permission to re-post this article which originally appeared in the Applied Infrastructure blog under


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Nick Kelly

Cybersecurity Engineer, Cisco

Nick has over 20 years of experience in Security Operations and Security Sales. He is an avid student of cybersecurity and regularly engages with the Infosec community at events like BSides, RVASec, Derbycon and more. The son of an FBI forensics director, Nick holds a B.S. in Criminal Justice and is one of Cisco’s Fire Jumper Elite members. When he’s not working, he writes cyberpunk and punches aliens on his Playstation.


Virgilio “BONG” dela Cruz Jr.

CCDP, CCNA V, CCNP, Cisco IPS Express Security for AM/EE
Field Solutions Architect, Tech Data

Virgilio “Bong” has sixteen years of professional experience in IT industry from academe, technical and customer support, pre-sales, post sales, project management, training and enablement. He has worked in Cisco Technical Assistance Center (TAC) as a member of the WAN and LAN Switching team. Bong now works for Tech Data as the Field Solutions Architect with a focus on Cisco Security and holds a few Cisco certifications including Fire Jumper Elite.


John Cavanaugh

CCIE #1066, CCDE #20070002, CCAr
Chief Technology Officer, Practice Lead Security Services, NetCraftsmen

John is our CTO and the practice lead for a talented team of consultants focused on designing and delivering scalable and secure infrastructure solutions to customers across multiple industry verticals and technologies. Previously he has held several positions including Executive Director/Chief Architect for Global Network Services at JPMorgan Chase. In that capacity, he led a team managing network architecture and services.  Prior to his role at JPMorgan Chase, John was a Distinguished Engineer at Cisco working across a number of verticals including Higher Education, Finance, Retail, Government, and Health Care.

He is an expert in working with groups to identify business needs, and align technology strategies to enable business strategies, building in agility and scalability to allow for future changes. John is experienced in the architecture and design of highly available, secure, network infrastructure and data centers, and has worked on projects worldwide. He has worked in both the business and regulatory environments for the design and deployment of complex IT infrastructures.