Voice over and/or under data?

In the Wide Area Networking newsletter Steve co-authors with Joanie Wexler, the topic last week was the emergence of DSL “Lite” services that provide less bandwidth than traditional asymmetric DSL services, but at a lower price. These services, which could be significant for teleworkers, raise some interesting questions about voice support.

First, a couple of basic assumptions. One of the justifications for moving to these services is that they are a great replacement for dial services, thereby saving money on traditional voice lines. Also, with the demise of companies like JetStream, we’re going to dismiss the specialized voice over DSL (VoDSL) as a great idea that won’t make it in the market.

That said, the support of voice in conjunction with DSL (and DSL Lite) services raises questions about possible dual modes.

For voice over cable modem, the choice of running VoIP over the cable modem is a no-brainer. It’s the only reasonable option.

However, with DSL services, by default you can run traditional voice over the same two wires that support the DSL service. We’ll call that “Voice Under Data.” You also can run VoIP over the data portion, a typical “Voice Over Data” implementation.

Think of the possibilities. In one scenario, you could have POTS service from your traditional local exchange carrier (LEC), and, over the same wire pair, you could have your connection to the corporate VoIP connection. However, you may also end up with two public services over the same connection. You can maintain your traditional analog POTS, but your DSL provider may not be the same company as your LEC. Consequently, you could end up with analog voice service from your LEC and digital voice service from your ISP.

But if you really want your head to spin, consider this option. Companies like Fujitsu are offering IP phones specially designed for IP Centrex services. It’s not at all unreasonable to think that you could have two branches of your ILEC competing for your business – with analog service in the baseband portion of the bandwidth, and one or more IP Centrex lines running within the data portion.