The tenacity of TDM

Despite the recent growth spurt in voice over IP (VoIP) adoption, few companies are going to completely dispense with time division multiplexing (TDM) technologies for phone service, an Avaya Canada executive said Friday.


years ago, VoIP was touted as a technology that could supplant TDM in corporate networks, said Tracy Fleming, a convergence specialist with Markham, Ont.-based Avaya Canada Corp.

But now, companies installing VoIP are using it only in select areas, such as wide-area connections, he added during a presentation at a conference titled Mobile Technology for your Business, held by the Toronto Wireless User Group (TorWUG).

“”We’re actually seeing customers rip out pure-play voice over IP systems,”” replacing them with hybrid VoIP and TDM systems, which allow certain advantages, such as redundancy.

“”The whole concept of voice over IP at one time was toll avoidance – ‘We’re going to screw the phone company,'”” he said to an audience of about 50 people.

In order to make VoIP work well over a wide-area network, Fleming said, users discovered they would need to add service level guarantees, which cost more money.

“”And guess where you buy the wide-area network service from? The same guys you buy your phone service from.””

Telecommunications carriers are now selling — and making profits from — IP services that include quality of service provisions. In some cases, Fleming said, VoIP has become more expensive than traditional services.

“”We now see a lot of people adopting the revolutionary new technology called voice over PSTN,”” he quipped.

Some companies use voice over IP only to route calls between far-flung office, and continue to use TDM for voice traffic within their offices, Fleming added.

Elevator manufacturer ThyssenKrupp AG, for example, routes its customer calls between its Canadian offices over Bell Canada’s Frame Relay network but uses TDM to route calls within its offices, Fleming said.

One company contemplating voice over IP to connect between cities is bond trading firm Shorcan Brokers Ltd.

Right now, the Shorcan uses an expensive trunk line to route calls between its Toronto office and customers in, said Bryan Araujo, a Shorcan technical support specialist. Araujo attended the TorWUG conference because his company may migrate VoIP for inter-city calls.

But after the conference, Araujo said he plans to investigate VoIP further, because he is not completely convinced it will provide a return on investment (ROI), once the equipment costs are factored in.

Calculating the ROI on VoIP is not an exact science, and varies from industry to industry, said Ronald Gruia, enterprise communications program leader for research firm Frost & Sullivan’s Canadian office. Gruia, who did not attend the TorWUG conference, agrees that toll bypass has become a less compelling selling point of VoIP.

The big question now is what will drive future growth, Gruia said. Although VoIP will let companies use applications that could not be used with TDM, it is difficult to convince business managers to make the investment, he said, adding companies that don’t install VoIP now will do so eventually because they will discover competitors who are using VoIP have certain advantages.

TorWUG director Craig Read said he hopes VoIP will make voice services less expensive.

“”I’m looking forward to a point where voice over IP starts beating up the monopoly providers,”” he said. “”You pay five times more for your telephone call than you need to because of regulations and taxes.””

Read praised Michael Powell, chairman of the U.S. Federal Communications Commission (FCC), for voting Thursday against subjecting voice calls between computers to the same regulations as telephony services.

He added the Canadian Radio-television and Telecommunications Commission (CRTC) should do the same for Canada in order to avoid stifling investment in broadband services.

“”In the United States, broadband development should start to take off,”” as a result of the FCC ruling, Read said.

In Canada, Primus Telecommunications is offering VoIP over digital subscriber line (DSL) and cable Internet connections under the TalkBroadband brand name, while Rogers Communications Inc. announced Thursday it would offer VoIP over cable next year.


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