Summary Signal
Adding a new OLT vendor to a live broadband network used to take six months. Deutsche Telekom and Türk Telekom are now doing it in days.
Both operators run their disaggregated access networks on VOLTHA (Virtual OLT Hardware Abstraction), the open source project hosted by LF Broadband. Türk Telekom’s own leadership describes theirs as the world’s first and largest live access network built on open source. Deutsche Telekom uses VOLTHA as a building block of its Access 4.0 transformation program.
In a session hosted by the Broadband Forum on April 6, Francisco De Carvalho walked through where VOLTHA sits in the operator landscape today, how the ecosystem is testing and certifying multi-vendor deployments, and how collaboration with the Broadband Forum is aligning open source code with the standards operators procure against. Francisco is Senior Director of Integrated Solutions at Radisys and sits on both the LF Broadband and Broadband Forum boards, so he sees both sides of that conversation firsthand.
The problem with vertically integrated broadband
Operators worldwide face the same pressure: deliver higher speeds, greater reliability, and faster innovation, while legacy, vertically integrated systems slow everything down. Vendor lock-in limits flexibility. Multi-vendor integration is expensive. Introducing a new hardware vendor into a traditional architecture can take six months or more.
Fiber expansion for 5G backhaul (and eventually 6G) compounds the problem. So does supply chain fragility, which the industry has seen play out repeatedly over the last decade. Operators who depend on a single supplier, or a single supplier’s roadmap, aren’t just taking a commercial risk. They’re taking an operational one.
“I manage a farm. I know if I have a single supplier, I’m going to get in trouble at some point. And it is the same in telecoms. You have a supplier of one, or as a vendor, you have a customer of one, you have a problem.” – Francisco De Carvalho, Senior Director, Integrated Solutions, Radisys
Disaggregation addresses this directly: hardware separates from software, control plane separates from user plane, compute separates from the solution. Combined with SDN, NFV, microservices, and cloud-native design, operators get the flexibility to mix vendors, contain costs, and move faster. But the approach only works if the APIs between layers are genuinely open.
That’s the gap VOLTHA fills.
What VOLTHA actually is
VOLTHA is production-grade open source software that provides a vendor-neutral hardware abstraction for PON broadband access equipment. It runs on Open Network Linux, uses Kubernetes and microservices by design, and communicates over gRPC for streaming telemetry and KPIs. It sits between northbound management systems (OSS, SDN controllers) and the OLT and ONU hardware below, exposing a consistent northbound interface across diverse access equipment.
The architecture is multi-vendor and multi-protocol from the ground up. It supports GPON, XGS-PON, and, with minimal changes, next-generation PON technologies including 25G and 50G PON. It works with both greenfield and brownfield deployments. Operators can download the software, install it, and run it independently. Vendors can build commercial products on top of it. LF Broadband provides support through to certification for members who need it, but nothing is locked behind a license.
The operator impact is concrete: adding a new OLT vendor to a live network goes from six months to days or weeks.
SEBA: the end-to-end reference design
VOLTHA sits inside SEBA (SDN-Enabled Broadband Access), LF Broadband’s flagship end-to-end reference design. SEBA defines a common architecture for software-defined, disaggregated broadband access, covering PON access, aggregation, and BNG functionality, with standardized northbound APIs. SEBA 2.0 was authored and backed by tier-one operators including Deutsche Telekom and Türk Telekom, and added disaggregated BNG functionality, enhanced scaling, and an expanded northbound API defining more than 40 NBI API calls. VOLTHA is the software implementation at the access layer; SEBA is the architectural frame that makes the whole thing deployable.
VOLTHA 2.15: what’s new
VOLTHA 2.15, released in February 2026, delivers features that directly address the operational realities of running disaggregated PON at scale:
- PLOAM-level ONU Disable/Enable. Operators can now isolate a misbehaving ONU at the PLOAM level without disrupting the rest of the PON. Two methods are supported: by serial number for ONUs not yet activated, and by ONU ID for those already on the network. This gives operations teams precise fault isolation during maintenance without service-wide impact.
- Enhanced Performance Management statistics. Metrics now better align with real-world vendor implementations. Frame-level counters replace packet-level counters where vendor definitions vary, XGSPON-ready FEC and GEM counters avoid overruns at line rate, and a new 64-bit KPI event supports reliable publishing of high-speed PON statistics across mixed-vendor deployments.
- OLT IP address update without reprovisioning. Previously, changing an OLT’s IP address required deleting and re-adding the device. VOLTHA 2.15 introduces a non-disruptive API call, reducing downtime during infrastructure changes.
- gRPC statistics across VOLTHA modules. Platform-level observability for control-plane behavior, supporting monitoring, troubleshooting, and capacity planning in large-scale deployments.
Beyond new features, the release includes significant stability work for high-density environments, including crash fixes in the OpenOLT and OpenONU adapters at 10,000+ ONU scale, reconciliation improvements, and logging optimizations across the stack.
A proving ground for multi-vendor interop
One of the most important developments for the ecosystem is the shared test environment in Berlin. The LF Broadband community testbed is hosted in Deutsche Telekom’s lab and was recently upgraded by BISDN. It provides a production-like setup used by the VOLTHA project for release testing, validating Deutsche Telekom’s and Türk Telekom’s VOLTHA use cases on live network configurations, and covering multi-vendor ONU interoperability and automated provisioning workflows.
Alongside it sits the i14y Lab, a neutral Berlin facility led by Deutsche Telekom together with a consortium of operators and partners, including Telefónica and Vodafone, and backed by German federal funding. i14y provides a broader interoperability testing environment that is increasingly being used for broadband disaggregation alongside its original Open RAN focus.
Together, these spaces give operators and vendors a shared proving ground before field deployment, catching integration issues in a lab in Berlin rather than in a live network and shortening the path from procurement decision to production.
Collaboration with the Broadband Forum
“Bringing the two together, making sure that we’re aligned with the data models using YANG, making sure that we’re aligned with the protocols, making sure that we’re aligned with the use cases is critical. And that’s what we’re doing.” – Francisco De Carvalho, Senior Director, Integrated Solutions, Radisys
The session underlined how LF Broadband and the Broadband Forum are formally converging. In 2022, a joint CloudCO demo at Network X showed VOLTHA integrated into a CloudCO environment via Broadband Forum specified APIs. VOLTHA 2.11 included the first BBF-aligned YANG models. In June 2025, the two organizations announced a formal initiative to align open source software with carrier-grade standards and Technical Reports, ensuring LF Broadband solutions comply with the specifications operators use in procurement.
Working Text WT-525, the Virtual OLT Hardware Abstraction Alignment with CloudCO project under the Broadband Forum’s Provider Cloud work area, is the document bringing this alignment into technical detail. Member companies including Adtran, Altice Labs, BISDN, Deutsche Telekom, Netsia, Nokia, Radisys, Türk Telekom, and Vodafone are participating. A new baseline is expected following contributions accepted at the most recent BBF member meeting.
Proof in production
Two tier-one operators anchor the deployed-at-scale story:
- Deutsche Telekom is using VOLTHA as a key building block of its Access 4.0 network transformation program, with a software-defined access network running on local edge cloud infrastructure with commodity x86 hardware and white-box switches.
- Türk Telekom has been described by its own leadership as operating the world’s first and largest live access network built on open source, using Netsia Broadband Suite. Netsia is a subsidiary of Argela/Türk Telekom.
Additional deployments are live across Europe, South America, and India. LF Broadband is actively engaged with around 250 organizations globally, from tier-one operators and regional providers to vendors and research institutions, with 17 currently qualified as interested in joining the fund.
What’s next: AI-ready by design
VOLTHA was built from day one to be AI-ready, with open APIs, vendor-neutral architecture, real-time telemetry, and support for closed-loop automation. LF Broadband isn’t planning to reinvent the AI stack; instead, the approach is to lean on existing Linux Foundation work and use VOLTHA’s open data surface to enable use cases like network optimization, congestion prediction, and real-time quality of service management.
The enhanced PM statistics and gRPC observability in VOLTHA 2.15 lay further groundwork for AI-driven operations, providing the accurate, real-time data feeds that predictive models depend on.
The takeaway
Open, disaggregated broadband is live, in production, and being extended by commercial vendors. The LF Broadband community testbed and the i14y Lab give operators and vendors a shared proving ground before field deployment. The BBF alignment work, including WT-525, is connecting open source code to the standards operators procure against. For service providers still locked into vertical silos, VOLTHA, and SEBA around it, is the fastest route to a multi-vendor, multi-protocol, future-proof access network.
Faster innovation cycles. Reduced costs. Supply chain flexibility. The ability to shape the future of open broadband access. That’s why operators, vendors, and researchers are joining the VOLTHA community.
Watch the full session
The recording is available on the Broadband Forum YouTube channel. To learn more about LF Broadband membership or get involved with VOLTHA, visit lfbroadband.org.
About VOLTHA
VOLTHA (Virtual OLT Hardware Abstraction) is an open source project hosted by LF Broadband that provides a vendor-neutral hardware abstraction for PON broadband access equipment. Built on Kubernetes and microservices, VOLTHA exposes a consistent northbound interface across diverse OLT and ONU hardware, enabling operators to deploy and manage multi-vendor PON networks through a single control and management framework. VOLTHA supports GPON, XGS-PON, and next-generation PON technologies, works across both greenfield and brownfield deployments, and is proven in production at tier-one operators including Deutsche Telekom and Türk Telekom. VOLTHA reduces vendor onboarding from six months to days or weeks and aligns with Broadband Forum specifications for integration into CloudCO environments.
About LF Broadband
LF Broadband is a neutral home for collaborative development of open source software for the broadband access industry. Part of the Linux Foundation, LF Broadband supports projects transforming broadband networks and the Passive Optical Network (PON) industry, including VOLTHA, the open source hardware abstraction for virtualizing multi-vendor PON systems, and SEBA, the reference design for software-defined, disaggregated broadband access. Its members include tier-one operators, hardware and software vendors, and research organizations working together to deliver open, multi-vendor, carrier-grade broadband. LF Broadband works in close alignment with the Broadband Forum to ensure open source solutions comply with carrier-grade standards operators use in procurement. Learn more at lfbroadband.org.
Last updated: April 2026
AI Disclosure This post used artificial intelligence tools for the webinar transcript, project research, structural assistance, or grammatical refinement. The final content was reviewed, edited, and validated by human contributors to LF Broadband to ensure accuracy and alignment with our community standards. We remain committed to transparency in the use of generative technologies within the open source ecosystem.
