In my last column, we tried on Voice over DSL (VoDSL) for size. We concluded that VoDSL could prove advantageous, if provided with broadband data services.
For the longer term, however, what SOHOs and small businesses are really looking for is a way to bring digitized and compressed voice and video directly from the premises to large voice-ready IP backbones without moving through any legacy technologies.
According to DSL Reports, one of several valuable DSL information sites on the Internet, my ideal case scenario -- packetized voice as well as data -- can be built, but is not currently a commercially viable option.
There are two commercially deployable forms of VoDSL. A VoDSL provider can run voice on a DSL connection straight to a voice/data gateway in the central office, at which point the digital signal is sent to any voice switch for standard voice transmission over the long distance network of my choice. Alternatively, the voice packets can go to a digital subscriber line access multiplexer (DSLAM) where they merge with packets from other DSL lines, which in turn are all sent to the voice switch. At the DSLAM, the Internet (data only) connection usually goes to an IP carrier's backbone.
The primary reason that carriers don't offer packetized voice over DSL today is not, in fact, the prohibitively high cost of the local broadband access, but rather two other simple reasons. First, the quality of service we have on voice circuits today cannot be guaranteed when voice packets are mixed with data traffic; second, the supplementary services customers have grown accustomed to (and can have with VoDSL), such as voice messaging, call waiting, and caller ID, are not supported in today's commercial VoIP infrastructure.
I suspect that VoDSL, like other emerging communication services, will be an important way for service providers to differentiate themselves in the next two to three years, but within five years it won't make business sense for many operations. When data network access costs are higher than voice access costs, VoDSL will not be a significant value add. At that time, my vote would be to switch again. Those averse to technology risks should stay with POTS and only sign up for more robust, 100-percent VoIP service when available.
Bottom line: small offices, like businesses with thousands of employees, need VoIP service to bypass local providers for voice and data, and to connect them directly with a lower-cost VoIP network for long-distance calls. They won't find a long-term solution in VoDSL.