What is a Class 4 softswitch?

A Class 4 softswitch is a carrier-grade switching system that routes large volumes of voice traffic between networks — connecting carriers, VoIP providers, and telecom operators at the wholesale level. Unlike Class 5 switches, which handle end-user features like voicemail and call forwarding, Class 4 systems are purpose-built for high-capacity transit routing, least-cost routing decisions, and inter-carrier interconnection. 46 Labs' PeerEdge Voice Infrastructure replaces legacy Class 4 hardware with a software-defined environment that gives carriers real-time routing control without on-premise hardware constraints.

How does SIP replace TDM in a carrier network?

Session Initiation Protocol (SIP) replaces Time Division Multiplexing (TDM) by moving voice traffic from dedicated copper circuits to IP-based packet networks. TDM allocates fixed bandwidth per call regardless of whether it's in use; SIP dynamically allocates bandwidth only when needed, dramatically reducing cost and improving scalability. Migration typically involves replacing TDM gateway hardware with SIP trunks, re-provisioning routing tables, and validating STIR/SHAKEN compliance on the new infrastructure. 46 Labs manages this migration process end-to-end, mapping every trunk and rate table before cutover to eliminate service disruption.

What is a carrier-grade SBC?

A Session Border Controller (SBC) at carrier grade is a network element that sits at the edge of a carrier's IP infrastructure to manage, secure, and route SIP traffic between networks. It handles signaling normalization, encryption, transcoding, and fraud prevention at scale — processing millions of concurrent sessions while maintaining call quality and regulatory compliance. Carrier-grade SBCs differ from enterprise SBCs in their capacity requirements and multi-tenant architecture. PeerEdge Voice Infrastructure includes carrier-grade SBC functionality as part of its core switching environment.

What is STIR/SHAKEN and why does it matter for carriers?

STIR/SHAKEN (Secure Telephone Identity Revisited / Signature-based Handling of Asserted information using toKENs) is the FCC-mandated framework that authenticates the caller ID of calls traversing the PSTN. Carriers are required to implement STIR/SHAKEN to sign and verify calls passing through their networks, reducing robocall fraud and improving consumer trust. Non-compliant carriers face FCC enforcement action and may be blocked by downstream providers. 46 Labs' infrastructure is built with STIR/SHAKEN compliance integrated, not bolted on.

What is wholesale voice termination?

Wholesale voice termination is the service of routing and completing call traffic originated by one carrier onto another carrier's network, ultimately delivering the call to its destination. Wholesale termination is typically sold in bulk at per-minute rates and is the core commercial model for carriers operating Class 4 infrastructure. 46 Labs provides wholesale voice termination with automated least-cost routing, real-time quality analytics, and vendor management tools through PeerEdge Voice Infrastructure.

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Preparing for the Copper Phase-Out

Bridge the gap between legacy TDM and modern IP networks with 46 Labs Tandem Services — keeping every community reachable while you modernize.

Thanks to today’s digital infrastructure, copper phone-calling is definitely on the way out.

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However, that could lead to some initial road bumps. For example, a phone call to a rural community could fail just because the networks on either side run on completely different generations of tech. Yet as tier-1 carriers accelerate copper decommission, keeping calls connected gets complicated fast.

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Small regional providers and national giants operate at very different speeds. At 46 Labs, our Tandem Services bridge that exact gap — linking traditional Time-Division Multiplexing (TDM) networks with modern IP infrastructure seamlessly. And for us, this isn’t theoretical. Because over the years of growth and acquisitions, we’ve actually done this several times - keeping networks connected while progressing through a digital transformation.

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It’s important to know that the sharpening of the copper phase-out timeline is due to regulatory shifts and mandates. The FCC’s Network and Services Modernization Order streamlines rules for retiring legacy networks, with key provisions kicking off earlier this year on May 20, 2026. There isn't a single "off switch" date where every copper line goes dark nationwide — schedules vary by region and provider. But the practical reality is immediate: carriers must audit legacy interconnections and establish replacement routing paths long before physical cutovers begin. In reality, by 2030 there will be little to any copper left.

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Bridging these systems requires infrastructure that works on day one. Through Federated Tandem, 46 Labs combines TDM access with native IP interconnections across major national carriers and CLECs. In a single managed platform, carriers get nationwide traffic reach, simplified call routing, and built-in failover redundancy without forcing expensive hardware overhauls on remote partners.

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For carriers migrating off copper, our managed TDM-to-SIP Transformation service handles the protocol conversion and signaling translation on the fly. We operate the SBC infrastructure, gateway architecture, and call-quality analytics behind the scenes. This allows regional and rural operators to transition in stages — protecting margins without buying, deploying, or maintaining legacy gateway hardware that’s already on borrowed time. Couple all of this with our first-hand experience, and the copper phase-out isn’t something you or your customers will have to worry about.

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Read more about Tandem Services