Digital Subscriber Line (DSL) has evolved from a high-speed Internet technology to a high-speed multiservice access technology, capable of simultaneously delivering a variety of dissimilar services over the same existing copper wire. Alongside Internet access, one of the first new services to be deployed over DSL is voice.
With voice services comprising a larger percentage of small and medium business expenses than data, Local Exchange Carriers, both Incumbent (ILEC) and Competitive (CLEC), are looking into the possibility of bringing Voice over DSL (VoDSL) to their customers.
“Imagine the huge advantage a service provider would gain if on a single copper pair, they could deliver to your office 16 voice lines and still manage to provide you with high-speed Internet access,” said Louis Lambert, country manager for Canada with Santa Clara, Calif.-based vendor, CopperCom.
One national CLEC, Toronto-based Optel Communications Corp., said it was looking at deploying VoDSL across Canada.
“Optel is going national, we are a national-based CLEC,” said Dan Roy, Optel’s chief information officer. Optel will be in 110 co-locates by year’s end expanding its footprint, he added.
“Optel’s service market is strictly the small- and medium-sized businesses. That market has served us well,” said Roy. “We found that this was an underserved market in the first place and the first-to-market advantage in this segment certainly creates a lot of loyalty.”
At 30,000 feet VoDSL technology is pretty simple, said Lambert. The voice signal from the customer telephone is converted into ATM packets and transported over the DSL connection. At the central office the signal is converted back to voice and fed to a telephone switch.
“This is not black magic; it is using the latest in voice compression, driven by the robustness of the Asynchronous Transfer Mode (ATM) protocol over DSL connection,” said Lambert.
Unfortunately, there are a few obstacles arresting the deployment of this technology, QoS demands topping the list. After all, DSL is simply modem technology and businesses demand toll-quality voice.
“I think it’s (technology) getting there pretty fast. I don’t know that it’s quite there yet or at least the perception that it’s quite there yet isn’t there,” said DSL research analyst Adam Guglielmo with Tulsa, Okla.-based consultancy TeleChoice Inc. “A few problems with it is that you are still running through a gateway then running through a Class 5 switch so the hand-off fees are still there.”
He added that a shift from permanent virtual circuits (PVC) to switched virtual circuits (SVC), and a direct route from the gateway to a Class 3/4 switch would get rid of hand-off fees, driving prices down. But, the true test will be convincing people that it’s a viable technology at this point. “When the big Bells get into selling Voice over DSL services is when it will really take off,” he said.
Echoing some of Guglielmo’s concerns Roy said, “The biggest hurdle is to get the mindset moved to the new technology.” However, he added, “Initially when we first started these trials we did have some problems, but as of today, those problems have been resolved. We’re beyond that.”
The greatest concern for carriers is the provisioning of more and more voice channels, even at the far-end of the DSL reach, where available bandwidth is low, while providing toll-quality voice, said Lambert.
“Voice-compression is the single most important element directly affecting backhaul cost savings and increased market reach for simple voice and Internet connections,” he said.
“In Canada, in general, the reach is the problem,” said Roy. “We don’t have the population base that the U.S. has where you could deploy this and get your payback that much quicker.” He added, “Basically, this represents to us the opportunity to…increase the customer service, and have a QoS that can be guaranteed.”
TeleChoice’s Guglielmo said that toll-quality should be the greatest concern for any company deploying VoDSL. “I think it’s (technology) pretty close, they have to get it there otherwise it’ll never take off. If you talk to the vendors they’ll say they’ve conquered these things, whether that equipment is out there yet in its latest iteration that has gotten rid of these technology issues like echo cancellation, cross-talk interference, remains to be seen. They say they’re at carrier-class now, but until it’s out there and we start to hear back from consumers how they feel about the service, how well the service is actually working, it’s really hard to tell.”
VoDSL rates will vary depending on the provider, but most see the data access as becoming a free option once costs begin to drop. For more information on DSL, visit Optel Communications at
, Telus at
or CopperCom at