Match, Surpass PSTN Voice Quality: Sounds Like a Plan for VoIP

Carl Weinschenk

Carl Weinschenk spoke with Tom Flanagan, director of technical strategy for Digital Signal Processor Systems, and Debbie Greenstreet, director of service provider strategy for Digital Signal Processor Systems, Texas Instruments.


Weinschenk: Where does the VoIP industry stand in relation to voice quality?
Flanagan: I think we can segment this into a couple of markets. In the enterprise space, I think voice quality is really in very good shape. The primary reason is that all the components in the network are pretty well understood and managed from the top down. Where we hear more about the challenge is in residential services. The primary reason is that the last mile connection is unmanaged and uncontrolled. The last mile is where a lot of challenges come in. The other factor is that consumer-oriented services are very, very complex, with more elements than the enterprise has - especially the addition of session border controllers. Quality is a huge initiative for us. Quality centers on having proper instruments in place across the network that really drill down and solve problems. One of the frustrations the industry has is that very good tools are available to provide instrumentation for operators or IT managers to understand what is going on from the end user perspective. Most of those are not being implemented.


Weinschenk: What happens once the public switched telephone network (PSTN) and VoIP reach quality parity?
Flanagan: Overall, we would not make any progress if quality was not at least on par with the PSTN for the vast majority of calls. I believe that's where we are, particularly in the enterprise case. There, once we reached parity, we've got a really nice infrastructure in place and are able to go beyond the PSTN. What we [then] are looking at is wideband technology in the phone. Now we are addressing audio quality and taking the voice experience [far higher]. The analogy is from AM radio to listening to a CD. We can get that quality using wideband codecs. Think of it as high-definition VoIP. It's kind of ironic that voice is the last to embrace the high-definition format. The broadband connectivity at the endpoint allows us to do wideband end-to-end.


Weinschenk: Why are the remote monitoring capabilities important?
Greenstreet: Having the ability to have some level of reporting of quality of the experience of the end devices [is important]. Some companies don't have staff at remote sites. They may want information on quality on the phone or the voice gateway in a small business or in the home. We have the ability to do troubleshooting on networks that are a bit more complicated than voice service using TDM. It's what we call quality of experience reporting and troubleshooting, if there is a problem. And another thing to be considered is that now in this network there is more SIP-based technology, which is more distributed. We need to understand the maturing of the equipment being used because of the distributed nature of the SIP network and its interoperability and feature support capability. One thing we are seeing is that operators - more on the residential and small business sides - tend to focus on low-cost CPE devices and not on the overall robustness of equipment. That may save money [upfront] but cost you more in the end.

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