The One-Way Audio VoIP Dilemma

One-way audio is an annoying anomaly where one person can hear the other caller, but that caller can't hear them.  It is uncommon in non-VoIP telephony, but seems to occur frequently in systems that have just been deployed.

In traditional TDM voice transmissions, the circuits are reserved for two-way voice transmission, but in VoIP each voice stream is independent.  Should one of the streams be lost, deferred, or misdirected, the call the results on has one active stream in one direction.

The most common reason for one-way audio is the result of improper negotiation of the RTP voice stream by a server that is behind a firewall - an unaccommodating firewall.

In a future post we will talk about how to isolate the offending firewall and how to work with the system or firewall administrator to set NAT parameters appropriately so that both RTP streams can be negotiated successfully.

Attacking VoIP Call-Quality Issues

Call-quality issues are a bit trickier with VoIP than with traditional telephony.

One of the main problems with VoIP are the negative effects of the delays in transmission of packets.  The latency is always inherent in converting a call to and from VoIP.  But no matter how quickly that conversion occurs, if there are several, the cumulative effective latency can have noticeable degradation in quality.  An end-to-end cumulative latency of great than 200 milliseconds (ms) causes human perceptible delay and results in conversations with participants that repeatedly interrupt each other.

Fluctuations in latency are also common on VoIP networks.  This is commonly referred to as jitter.  Jitter is in most cases caused by a leg in the call path that is sharing traffic with other applications or calls.  The most common  symptom of jitter is called "clipping."

A normal conversation sounds like this:
"Hi dear, shall I stop at the store to pick up some milk?"
but clipping produces:
"I ear, all op de ore ick om ilk"

In future posts we'll explore how to isolate latency and jitter to one or many legs of a VoIP call.

The Essence of VoIP Issues

In the telephony world VoIP is a hybrid.

A VoIP solution usually has dedicated Internet connections, dedicated T1 voice circuits, and at two or or more points in a call a digital to analog conversion.

On top of these common telephony components, you add the complexities associated with IP packets:  latency, real time transport of packets, call control channels translations, and dial plan nuances.

One of the first questions to ask yourself when troubleshooting a VoIP call is whether or not a problem exhibits itself on all of your calls or just select ones.

In future posts we will begin to begin to isolate trouble to the various components of the call circuit and learn what clues to look for with each isolated issue or problem.

The True Customer Experience of a Voice Service

Customers perceive the quality of a voice service and the reliability of a voice service based on many different experiences. Such experiences may be good or bad, but very often customers notice only the bad experience – obviously as they buy a service that is meant to work 100% at any time and from anywhere.

Bad experiences are often caused by network related problems:

• Calls with degraded voice quality
• Interrupted or Dropped calls or VoIP Dropped calls
• Unsuccessful call attempts
• Missed calls that did not ring or calls that were not signaled

Also end device related problems bring negative user experience:

• Empty battery on smartphone
• End device & VoIP Endpoint crashes
• Inability to setup 3 party conference call

For all voice operators, over-the-top (OTT) and legacy networks, these end-device related troubles are very important. Because in the end the customer does not care at all why something is not working! He will blame it on his voice service provider anyway.

As a result when considering the management of customer experience in next generation voice networks, it is very important to look beyond your own network infrastructure. Internet connections, utilization and network problems on the customers’ corporate LAN and end devices cause a large portion of the problems. So it would definitively not be a good idea to consider a service running well, simply because in one’s own network, all systems are up and running.

Instead operators also need to manage:

• End device & VoIP Endpoint firmware versions
• App/softphone software versions
• IP link quality characteristics
• Performance and problems at your Customers’ premises
• Error logs from the end device

Very often problems can be solved by optimizing configurations, codec settings, centralized firmware updates or pro-actively contacting the customer about up-coming problems with his device or software. So a tool is needed that see the endpoint or VoIP device as well as the network. But for all of that, a customer experience management system must provide the full set of information about how the customer truly perceives the service End-to-End.

When looking at customer experience management for VoIP networks, operators should choose a holistic approach and carefully select software solutions that are designed to look far beyond the usual scope and take care about the most important stakeholder in this game – the customer.

VoIP Service Assurance Available in the Cloud

Due to the huge amounts of traffic, telephone network analyzers are complex systems with beefy hardware requirements, complex setup procedures and the need for constant monitoring. For bigger networks the costs to run them is easily worth it, but for smaller networks deploying them might not be feasible. Be it for lack of time to learn how to run them, or because of a too big initial investment.

A recent trend in IT is the introduction of cloud services including for example cloud based service assurance or cloud based VoIP troubleshooting. In this setup the main part of the analyzer system is run in a central system, where it is managed by a knowledgeable and dedicated staff experienced in network monitoring and efficient VoIP troubleshooting. This leads to rapid deployment times and minimal investment to the point where one can just 'Try before you buy' so in other words, troubleshooting on Demand. The advantage of economy of scale brought by cloud based Network Management or cloud based Network Monitoring makes the most advanced analyzers available for even the smallest VoIP providers, leveling the playing field for all. You can even install it at the last minute in just a few seconds and use it when you have a problem

By deploying a VoIP traffic analysis in the cloud, you can usually achieve up-times far better than by using a complicated local setup and you can make sure that your running costs stay predictable. With today's technologies, security and data safety are a well-managed issue, all traffic streams being encrypted. A centralized software setup or hosted service assurance makes updates easier and your service provider is also able to diagnose and fix problems more efficiently by having complete access to the stack.

Cloud-based service assurance or network monitoring or VoIP troubleshooting can now be made available on a pay for use basis. Basically, you pay when you login to troubleshoot a problem on your network. If you do not have a problem, do not ever log in, you do not pay a cent. If you do login, for a small charge for one use, you fix the urgent problem that is troubling your customer. The return on investment for use of the network troubleshooting service is instant. The advantage of having paid the Per-Use fee is obvious to your management, because you have just fixed a difficult problem impacting your voice service. Keeping your customer, your customer and allowing you to move on to creating a new service or engineering your network

Cloud-based network monitoring gives you universal visibility and centralized and universal access to the analysis. One Installation and setup is so rapid it can be used on-demand when needed i.e. VoIP troubleshooting on Demand. In summation, cloud computing brings lots of advantages to VoIP service providers, (ITSP’s) who could not previously afford or justify the expense for a traffic analysis. With generally better availability, a transparent pricing structure (based on usage) and better support options, cloud solutions are surely an understandable trend in today's VoIP software stack market.

Network Visibility Matters

“Knowledge is power” as the phrase goes and effectively, no matter what you want to achieve in your network management, a truly in-depth knowledge about your network processes is THE key asset when it comes to offering an excellent Customer Service and troubleshooting or to managing the overall network health with ease. Network knowledge and visibility allows you to find problems in minutes rather than hours, reducing operations costs and impressing your customer with rapid resolution of problems.

Today’s fast evolving telecommunication market with its multiple video & audio streams, a fast growing user base and geographically dispersed deployments is challenging and keeping an eye on the entire network doesn’t seem to be an easy task. Often, telecommunication operators are recurring to different systems or are not able to track back single network incidents which don’t provide a satisfying network visibility in the end.


First, choosing a solution that is able to process all signaling messages traversing the network in real-time and that instantly correlates multiple sites and network protocols is vital. Also, you will want to know the detailed status of the entire network health, the different application layers of the network, the end user devices and all the segments that a media stream is traversing through. A fully correlated end-to-end overview of all parts in the network can easily be provided when distributed agents are installed locally enabling a quick root-cause detection of network issues.

Talking about visibility, it is not only helpful to have an overall view of what is happening in the network, drilling-down into single calls, users, end devices and network devices is very valuable information as well. The perspective should be changed easily from a high-level overview for e.g. the operations department down to a granular and in-depth view of an individual user and its history which is helpful information for the customer service or support department. A filtering option will furthermore provide a high value to track users or to search for specific devices, numbers or customer groups, we which are known as realms.

A powerful network management tool should be able to provide past information about historical data, process data in real-time and should also allow a current and future proactive network management. Finally, a future-proof solution is a system which is easily integrated into an existing infrastructure reducing hereby the complexity, and instead of installing more hardware, it should be a lightweight solution that smoothly grows with the network.

A real-time intelligence software suite increases the ROI of LTE, IMS and VoIP deployments. It provides fixed and mobile operators a full end-to-end visibility and supports a multi-site and protocol call correlation.

Visualizing a VOIP Security Attack

Visualizing a cyber attack on a VOIP server from Ben Reardon, Dataviz Australia on Vimeo.
Prevent a VoIP security attack on your systems!