Cable Operators Choose DOCSIS 4.0 Upgrades Over Fiber Builds

Cable operators beyond the two largest US players are choosing DOCSIS 4.0 upgrades of their existing hybrid fiber-coax networks instead of building fiber to the home. Access-equipment vendor Harmonic (HLIT) and European cable operator Liberty Global (LBTYA) described the same shift from opposite sides of the market on their third-quarter 2026 earnings calls, held on November 2 and November 3, 2026.

Why cable operators face a DOCSIS 4.0 or fiber decision now

Cable broadband runs on a hybrid fiber-coax (HFC) network: fiber carries traffic from the operator's hub to the neighborhood, and the existing coaxial cable covers the final stretch into each home. A device in the hub called a CMTS (cable modem termination system) manages every subscriber's data signal. DOCSIS is the transmission standard for these networks, and its latest generation, DOCSIS 4.0, lets the same coaxial cable deliver multi-gigabit speeds. One of the most widely used legacy CMTS platforms is Cisco's (CSCO) cBR-8. Operators could no longer buy it directly from Cisco as of April 11, 2026, and July 11, 2026 was the last ship date [1].

An expiring platform and multi-gigabit competition force operators into a network decision. They can replace the whole network with fiber to the home, or they can keep the coaxial drop, swap hub equipment for a software-based virtual CMTS and upgrade the amplifiers and nodes along the line to DOCSIS 4.0. Liberty Global's view is that where cable is buried directly in the ground, without existing ducts, the upgrade path is far cheaper [2]. Every operator still running legacy equipment faces the same choice. Midco, a regional US operator and long-time Cisco customer, has decided to move to Harmonic's virtualized platform [1].

Operators launch at scale and vendor revenue spreads beyond two customers

Liberty Global supplied the operator-side economics. Its Dutch subsidiary Ziggo now sells DOCSIS 4.0 service, which management called the technology's first major launch worldwide. Ziggo is delivering 4 and 8 Gbps speeds today and will ultimately reach 8 million homes [2]. CEO Mike Fries said DOCSIS 4.0 costs one-tenth as much as building fiber, so the network-wide speed upgrade fits inside the current capital spending envelope [2].

Harmonic's revenue mix shows orders spreading out. Its top two customers still accounted for 54% of third-quarter revenue, but revenue from all other customers, which Harmonic calls "rest of market," rose 101% year over year to 46% of total revenue and made up more than 60% of the quarter's bookings [3]. Harmonic added nine customers in seven countries during the quarter. They include TDC, Denmark's largest telecom company, which picked Harmonic's platform for a unified DOCSIS 4.0 upgrade, a tier-one operator in Belgium, and Liberty Latin America [3].

The two sets of figures point the same way, but the direct link between them is limited. Ziggo's outside-plant amplifiers come from Helsinki-listed Teleste, not Harmonic [4]. Harmonic's overall book-to-bill ratio was only 0.7 in the third quarter, with rest of market around 1.0, and its backlog including deferred revenue fell from $587.6 million to $534 million [3].

Access-network spending shifts from fiber construction to software and line equipment

When an operator upgrades its coaxial network, part of the money that would have gone into trenching and laying fiber shifts to three groups of suppliers: virtual CMTS software in the hub, amplifiers and nodes along the line, and the RF chips inside that equipment. For vendors, the customer base widens from a few large US operators to regional and international operators, which lowers revenue concentration. For operators, multi-gigabit speeds become reachable inside the existing budget, which eases capital spending pressure [2][3].

This analysis holds only for networks with directly buried cable. Virgin Media O2, Liberty Global's UK joint venture with Telefonica, runs its lines through existing ducts, and its CEO said that in the UK it is simply cheaper to build fiber than to deploy DOCSIS 4.0 [2]. Rising memory prices are also leading some operators to push out their replacement decisions [1], and they cost Harmonic about $3 million a quarter [3]. Two metrics are worth tracking: whether Harmonic's rest-of-market revenue becomes the majority of its business, as the company expects, and whether its book-to-bill ratio returns above 1 [3].

Companies that could be affected

• Vistance Networks (VISN): The former CommScope access-network business. Its Aurora Networks unit sells DOCSIS 4.0 amplifiers and nodes and won a three-year European distributed-access program [5]. Every coaxial upgrade requires this kind of line equipment, but the unit's second-quarter sales of $319 million were still down 1% year over year as declines in legacy products offset growth in new ones [5].
• MACOM (MTSI): Supplies RF components to amplifier and node makers. Management said in August that its cable infrastructure business is growing about 40% this year [6]. MACOM sits one layer further back in the upgrade chain, and the business is a small share of company revenue.
• Liberty Latin America (LILA): A cable operator serving more than 20 countries and territories in Latin America and the Caribbean, facing the same upgrade-or-fiber choice. Harmonic said Liberty Latin America selected its DOCSIS and fiber platform in the third quarter [3], but Liberty Latin America did not mention the program on its own second-quarter call [7].

Sources

[1] Light Reading · Clock ticks for cable ops as Cisco's flagship CMTS nears end-of-life · 2026-09-29 · Industry media report · https://www.lightreading.com/cable-technology/clock-ticks-for-cable-ops-as-cisco-s-flagship-cmts-nears-end-of-life

[2] Drillr · Liberty Global (LBTYA) · 2026-11-03 · Q3 2026 earnings call

The world's first major launch of DOCSIS 4, which is now delivering 4 and 8 gigabit speeds today and will ultimately reach 8 million homes. This strategy, I have to say, validates both the quality of our HFC networks and the decision not to build fiber in this market.

[3] Drillr · Harmonic (HLIT) · 2026-11-02 · Q3 2026 earnings call

[4] Advanced Television · Teleste to supply VodafoneZiggo's DOCSIS 4.0 upgrade · 2025-07-14 · Industry media report · https://www.advanced-television.com/2025/07/14/teleste-vodafoneziggo-roll-out-next-gen-docsis-4-0-broadband

[5] Drillr · Vistance Networks (VISN) · 2026-08-06 · Q2 2026 earnings call

[6] Drillr · MACOM (MTSI) · 2026-08-06 · Fiscal Q3 2026 earnings call

[7] Drillr · Liberty Latin America (LILA) · 2026-08-06 · Q2 2026 earnings call

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