“Everyone’s getting rid of it.”
That’s how one carrier I spoke with described aging technologies like SONET/SDH and TDM.
Another used the term “accelerated outphasing,” while a third opted for a simple “RIP.”
The trend is clear. We're finally witnessing the retirement of SONET/SDH and TDM in carrier networks. (It's a big enough trend that it's impacting the way we approach our pricing research.)
Carriers are no longer investing in these platforms, and the focus is on facilitating migration to more efficient and flexible packet-optical networks. While there will be pockets in the global market where some level of support and specialized translation for SONET/SDH services will be required, it will be the rare exception. Technology in the data connectivity market has moved on.
For decades, the backbone of global telecommunications relied on technologies like synchronous optical network (SONET), synchronous digital hierarchy (SDH), and time-division multiplexing (TDM).
These robust, circuit-switched networks were the workhorses that carried our voice calls and early data traffic. But in the rapidly evolving digital landscape, their time has come to an end. The industry has reached a point of no return, actively decommissioning these legacy systems due to high costs and operational inefficiencies. Ethernet and optical wavelengths, while not new, have survived as the optimal transport technology services.
SONET, SDH, and TDM were revolutionary in their time, designed primarily for the continuous, predictable flow of voice communication. They allocated fixed bandwidth channels, which were great for phone calls.
But the internet changed everything.
Modern data traffic is "bursty." It comes in intermittent, high-volume packets. The fixed allocation of TDM networks meant vast amounts of bandwidth sat idle, leading to significant inefficiency.
Beyond this fundamental mismatch, several critical factors are driving their demise:
Two powerful transport technologies have replaced legacy networks to carry data traffic across core networks: Ethernet and optical wavelengths.
Originally a local area network (LAN) technology, Ethernet has evolved into a carrier-grade solution for wide area networks (WANs).
Its key advantage is statistical multiplexing, which dynamically allocates bandwidth only when data needs to be sent. This makes it incredibly efficient for handling the bursty nature of modern data traffic. Carrier Ethernet and MPLS are now the leading packet switching technologies for service providers, offering flexibility, interoperability, and cost-effectiveness.
This is where the real speed and capacity come into play. Optical wavelength services leverage fiber optic cables and advanced technologies like Dense Wavelength Division Multiplexing (DWDM). DWDM allows multiple high-capacity data streams to be transmitted simultaneously over a single fiber strand using different wavelengths of light. This capability provides:
Optical wavelength services are now the indispensable backbone for:
While the transition has been challenging, demands to scale networks to accommodate new traffic growth have forced customers to transition to more efficient, cost-effective services. The future of carrier network infrastructure is packet-optical. The sunset of legacy TDM/SONET/SDH networks is an essential step toward building a more agile, efficient, secure, and sustainable digital network that can support the ever-growing demands of our connected world.
TeleGeography’s Network Pricing Database is designed and maintained with these evolving technologies in mind.
Looking forward, our team will no longer support our Ethernet Over SDH or SONET and TDM data sets, choosing instead to focus on the intelligence that remains the most relevant and valuable to our users, whether they’re benchmarking their prices and procurement efforts against competitors, monitoring prices in new markets, or forecasting trends.
Our users can mix and match distinct, regularly updated network pricing on: