Open Source

VoIP Test Solutions: Is It Time for Them to Jump on the Open Source Bandwagon?

It is an open secret that the first choice of any new OEM or service provider in VoIP product or service rollout would be to use open source tools. The myth, though, is that the usage is restricted to new entrants, while established service providers prefer the variety of commercial products that are available in the market. While the significant role that open source tools played in making VoIP a reality cannot be undermined, what is still open to debate is whether they have compromised short-term cost benefits, time to market and flexibility with long-term product/service strategy and rollout.

However, the number of VoIP-based open source tools available speaks volumes about their popularity. On the flip side though, it can be argued that it has resulted in the problem of plenty, thereby resulting in confusion about the apt tool. Once the appropriate tool is identified, there is no denying the fact about its usefulness across different cycles, including production-related troubleshooting and root cause analysis.

Business Needs

Of course, service providers have varying business requirements depending on carrier and enterprise needs. The business need that drives carriers is the scale of their deployments, which are typically large. For enterprises, the services offered through VoIP, unified communications and contact center solutions, determine the success criteria.

But the all-important question that needs to be answered is: What exactly differentiates these tools?  You might be surprised. 

Judgment on a tool can be based on a number of factors such as:

·         type of tool: performance, feature, analysis;

·         platforms supported: Windows, Linux, Mac, Solaris/SunOS;

·         user interface: CLI, GUI; and

·         ease of automation: automatable, not automatable.

Classification can also be done based on factors such as:

·         language used to create tool: C, C++, Python, Java, PHP;

·         media support: RTP support or no media support;

·         transport options: UDP (News - Alert), TCP, TLS;

·         support for simulating complex scenarios like three-way call, call forward, call waiting and answer; and

·         support for tones and announcements: DTMF, hook flash, fax tone support, announcement support (IVR / stored media playback).

In addition to the above factors, tool selection also can depend on whether the tool can be used to validate only certain types of VoIP elements like client/server/proxy, or, if it can be used to validate VoIP network as a whole. Some open source tools are tuned for elements like servers and load balancers. Others are powerful enough and cater to the whole gamut of VoIP devices. Usage of such tools eliminates the need to deploy multiple tools for validation of the entire VoIP architecture.

The importance of ease of use cannot be underestimated either, as the industry is filled with testers with varying capabilities. While a section of testers would be comfortable executing complex commands and creating scripts for best usage of the tool, another group would be happy to use a well-exposed GUI in which all user interactions are very clear.

Tool Usage Across Industries

The choice of tools also varies based on whether they are being used by a service provider or an OEM.

Service providers have never hesitated to invest in commercial products, but the outlook on open source tools has certainly changed. A popular strategy in the market is to buy licenses for a limited number of ports/channels from commercial vendors and load the system under test with open source tools like SIPp. As an example, say a gateway or switch with peak capacity of 8,000 voice channels needs to be tested for voice quality. Instead of buying licenses for the entire 8,000 channels for speech quality measurement from a commercial vendor, licenses can be obtained for just 23 (one T1) or 30 (one E1) channels. The remaining 7,977/7,970 channels of the system under test can still be loaded by using SIPp. This results in a very cost-effective test environment without compromising on the quality of test output.

Simulation of the production environment in their labs is crucial for service providers. This includes conditions like high network traffic resulting in packet loss, network delay and jitter. There are tools such as NistNet, which can simulate these network conditions, thereby adding real-world feel to testing. It goes without saying that testing would be incomplete without such tools.

The biggest challenge for OEMs are that no matter how exhaustive their test coverage is, it still cannot address the numerous ways in which their product would be used by service providers. No OEM would ever replicate all service provider architectures in its labs. However, there is a continuous endeavor in plugging the holes in all their testing. When issues are reported from service providers, which are most often specific to their environment, it would be easier for vendors to simulate those conditions by using the right diagnostic tools. Tools like SIPp could also be used to tweak the signaling packets/headers, thereby generating conditions that are seen by service providers in the markets.

Power of Open Source (News - Alert) Tools

Many open source tools have a modular, extensible architecture, with limited functionality in core and optional modules or user created plug-ins to do the rest. This is helpful when new standards are released, as the tools make it easier to enhance the core library for validation of new scenarios. Open source also provides a good platform on which to create new applications via protocol stacks and libraries, which can be easily ported to different platforms.

Apart from aiding the functional and load testing needs, the automation capabilities of a tool is critical too. Many open source tools provide GUI as well as CLI interfaces for the usage. The CLI, when supported, gives a platform for automation engineers to programmatically start, stop and invoke call features. For example, users can create a simple library using a scripting language such as TCL/Perl wherein an open source tool such as SIPp can be remotely controlled. There can be methods created that can collect the call logs and even parse through them for validation.

Many vendors or service providers also use open source PBXs, which can be used to simulate many features available in proprietary PBX (News - Alert) systems. Asterisk is a typical example, which has many features including voice mail, conference calling, interactive voice response (telephone menus), and automatic call distribution. Another example is OpenPBX, which is an easy to install and configure PBX software platform that can simulate a small to medium business scenario. A complete messaging solution with voicemail, fax, e-mail pager, DTMF command shell and text-to-speech support can be created by using VOCP.

Considering the complete VoIP ecosystem, there are additional tools like BSDRadius, which is an open source RADIUS server targeted for use in Voice over IP applications. Freeside provides an open source billing, ticketing and account administration package for Internet service providers that now includes support for VoIP CDR rating and billing.

Vendors also have used numerous tools like PROTOS to check for vulnerability and ensure standard conformance. Tools dealing with security have been highly successful, given the onus on secure systems and networks.

Given all the great things about these open source tools, does it mean that they have bulldozed commercial vendors and lead in terms of market share? Surprisingly, the answer is still no. The following limitations have played a major role:

·         Support for these tools is lacking, when compared to what is offered by commercial vendors.

·         Some tools are not automation friendly, and given the investment that most of the industry leaders have made on building their automation strategy and libraries, this is a huge limitation.

·         Media support is limited for most of the tools. While they are very capable on the signaling front, lack of media (RTP) support has forced organizations to look at commercial vendors.

·         There is scope for improvement on the compatibility aspect with different operating systems.

In summary, commercial tools attract the test community with a packaged test solution, address specialized needs like speech-quality measurements, and provide good support for the issues faced. Open source tools have found a space for themselves due to flexibility, cost effectiveness and ease of use. Never before did testers enjoy so many options.

Prashanth Adiga and Gokul Krishnan are senior project managers for the engineering services business unit at Infosys Technologies Ltd. (News - Alert) (

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Edited by Stefania Viscusi