Tip-Toeing Into VoIP's Woolly Verbiage

When people start to get indignant about the way their competitors characterize a technology — especially one of mutual interest — it usually means one side is on to something, and the other side isn't at all happy about it.

Such is the case with voice-over-Internet protocol, or "VoIP."

Last week, a friend who writes about the telephone industry called, sounding vaguely indignant. How can cable possibly call its early VoIP work VoIP, he asked, when the IP portion of it stops at the headend, and doesn't yet go all the way to homes?

That's not voice-over-IP, he harrumphed. Cable should call it "IP transport with circuit switching."

Now that's

Cable's pursuit of telephone service as an advanced addition to its IP (Internet-protocol) passageway seems more a question of "when" than "whether." While AT&T Broadband and Cox Communications Inc. are the most active with respect to phone service right now (albeit not yet over the IP path), the buzz level among technologists up and down the MSO roster has been amplifying.

And, as the techno-buzz gets louder, new words to trip over seep in — usually at the precise moment you think you know what's going on.

The gibberish list for telephone technology is so dense and so lengthy, it can make even the most tolerant jargon-watchers shudder. That's no surprise, really. The telephone industry is twice as old as the cable industry. That's 50 more years to concoct and re-concoct acronyms and code words.

Just in case you've not yet run into the dizzyingly dull lexicon of the telephone world, here's a tiny sampling, and translation, of what's ahead: Soft switches. Line-controlled signaling (LCS). GR-303. Media-terminal adapters (MTAs).


Like so many other instances, the language of telephony and VoIP technology describes new ways of doing pretty much the same old things.

The whole notion of "packet-styled" voice service, and the telephony aspects of Cable Television Laboratories Inc.'s PacketCable project, for example, is to deconstruct the functions of a telephone switch into software. That way, MSOs can exchange phone traffic from their customers without ever having to get on or off the public switched telephone network, or PSTN.

This matters — to the wallet. The regional Bell operating companies (or whatever we call them now) make great piles of money at the entrance and exit points of their networks — a fact that, at one time, at least partly explained AT&T Corp.'s interest in buying Tele-Communications Inc. and MediaOne Group Inc. Both also had local networks capable of passing phone traffic, but without the steep entry and exit fees.

Back to this week's translatables.

A soft switch
does in software what traditionally takes a few million dollars worth of hardware to do: Connect one person's phone line to another person's phone line, so they can talk to each other.

At its core, a soft switch is a server, like so many other things in the digital world. Calling it a "class-5 capable" soft switch means it replicates, in software, the features noted in the front pages of the phone book — making calls, or getting call waiting, call forwarding and caller ID.

(A class-4 soft switch, on the other hand, replicates in software the stuff that happens between switches, which in the existing world are called "tandem" switches.)

Line controlled signaling, or "LCS," is more cable-specific, in that it helps those operators who already spent gobs of money on class-5 switches to segue into IP-delivered telephony, without stranding the original investment. An active discussion amongst participants in the PacketCable project at CableLabs, LCS uses a telephone protocol (or set of rules) known as "GR-303" to map the digital packets comprising a phone conversation into the big, expensive switch.


A multimedia terminal adaptor, or "MTA," is the thing that goes into the house. Picture a cable modem with RJ-11 phone jacks on the back. Phone calls move in and out of an MTA over the DOCSIS (Data Over Cable Service Interface Specification) signal path.

Because it can handle both broadband Internet and telephony, the MTA is one of those ideas financial analysts like: Two revenue-producing services, one box.

And because the MTA builds on DOCSIS — which trimmed cable-modem prices from the $700 range in the mid-1990s to the sub-$100 range now — it's likely to be gentler on the budget than, say, a digital set-top.

This is just a tiny, tiny fraction of the language that will accompany cable's foray into voice-over-IP over the next few years. As plans evolve, so will the methods to describe them.

With any luck, cable's VoIP advance can be done without resorting to the six and seven letter acronyms common to telephony sector. We could, for example, make an acronym of my telco writer friend's accurate, if strangely indignant, depiction of cable's VoIP work so far: IPTWCS.

But let's not.