Optical/IP Networks

Tracking the End of the TDM Era

Back in the summer of 1990, the tiny town of Shoup, Idaho, an isolated mountain burg in the Salmon National Forest, was home to the last manually operated telephone switch in the United States. Residents of the small, tight-knit community were thrilled to see a new digital switch installed because it promised a level of reliable connectivity they had never experienced. The replacement of that analog switch marked the end of an era. Now 20 years later, the end of telecom’s digital switching era is also in sight as network operators aggressively adopt IP technology to carry voice, data and video traffic.

Telecom providers are beginning to speed up the replacement of time division multiplex (TDM) networks for a couple of reasons. First, they are finding it increasingly difficult to get parts for digital switches, and the skill set needed to service them is beginning to disappear as knowledgeable workers retire. Second, and perhaps more importantly, telcos are changing their perception of IP: They no longer view it as a disruptive technology; rather, they are embracing it as means for delivering new services.

For the next few months, Light Reading will be operating a TDM Replacement Briefing Center, where you can follow the industry’s progress on moving toward a converged all-IP network for voice and data.

For an excellent overview of the topic, check out this new Heavy Reading white paper "Network Modernization in the Era of All-IP Networks." In the paper, Hodges explains the drivers for TDM replacement and examines softswitches and IP Multimedia Subsystem (IMS) as options for replacing TDM in the core network. Hodges also profiles three network operators in various stages of upgrading their networks.

Hodges also hosted a webinar in April, Evolving TDM Networks, which provides a good discussion of the challenges associated with TDM replacement:

Other recent Heavy Reading research shows just how quickly the end of the digital switch era is dawning. Hodges predicts that by 2015 more than 66 percent of local installed lines in North America will be served by VoIP technology, up from just 16 percent in 2010. See a recent analyst note about his research here:

And for some historical perspective, check out Hodges’s note from 2008:

Light Reading also provides ongoing news coverage of TDM replacement. For insight into the challenges network operators face in keeping up their aging TDM switches and the options they have moving forward, take a look at these articles by Light Reading's chief editor, events, Carol Wilson:

— Dawn Bushaus, Contributing Editor, Light Reading

purna 12/5/2012 | 5:04:52 PM
re: Tracking the End of the TDM Era

Does this "TDM Replacement" briefing center limit "TDM" to voice switches and voice lines or will it include TDM transport networks (e.g. SDH/SONET)?

seidnerilan 12/5/2012 | 5:04:51 PM
re: Tracking the End of the TDM Era

To follow up on Purna's comment, will it also include E1/T1 lines and sub-rate services, many of which are being terminated by operators around the globe? It would also be interesting to get a handle on the size of the market for these services, which are being decommissioned. How big are these legacy islands? 

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