Comms Alliance issues VoIP QoS guidelines

In a world first, Australia's Communications Alliance has issued guidelines on how to implement quality of service for VoIP.

Australia's Communications Alliance has issued two industry-backed guidelines for the delicate task of implementing Quality of Service for VoIP deployments.

The two guidelines address the challenge of using a single broadband connection to combine voice and/or video applications with less time sensitive applications such as web browsing and email. They specifically address voice and video traffic that transverses across more than one network.

The guidelines were issued by Communications Alliance, an industry body consisting of service providers, vendors, consultants and suppliers as well as business and consumer groups. They were developed by working committee comprised of representatives from the telecommunications industry and Government regulatory agencies.

The VoIP Guideline offers service providers an indicator of quality for VoIP services and information on factors that determine conversational voice quality on VoIP Services. The IP Guideline has been developed as a planning guide to help operators meet QoS performance objectives.

Australia is the first country in the world to develop such guidelines, says Communications Alliance CEO Anne Hurley, although they have been aligned with and built on international recommendations.

"With the growth of large VoIP deployments and the increase in IP telephony service subscribers, the number of VoIP calls that cross multiple networks will inevitably grow," says Hurley. "Similarly, many telephony service providers are migrating to IP core networks, and all-IP interfaces for the exchange of telephony traffic."

"In this changing environment, it is increasingly important for the industry to have guidelines that ensure cohesion between networks as well as the best quality of service for customers. The next important step will be the implementation and successful use of the guidelines by the industry. We would then expect improvements to end user experiences, particularly when calls traverse multiple networks."

The IP network guideline covers three traffic classes:

  • a "best efforts" class (similar to current internet services),
  • a managed class for time critical services with low tolerance for interruption (e.g. for applications such as interactive voice or video that need a steady, continuing flow of data for the application to operate well), and
  • another managed class for services that are still time critical but with slightly less sensitivity to interruption (e.g. for applications such as 'real time' or interactive data that need a short response time but can tolerate some variance).

The VoIP guideline defines a number of categories for voice services. It provides an indicator of voice service quality and contains guidance on the influence of a number of factors such as:

  • delay (the time from mouth to ear),
  • echo (the amount of speech reflected back to the speaker),
  • codec choice (the method for converting speech into electrical signals and back again) and
    loss (the amount by which the electrical signal fades as it travels along a line) to come up with this indicator.

Copies of the Guidelines are available for service providers to download at:


Read more on Voice networking and VoIP