Last updated: May 2026. This guide is updated regularly as cable providers announce new DOCSIS 4.0 markets and milestones.
Key Takeaways
- Comcast (Xfinity) is the only major ISP with widespread DOCSIS 4.0 service today, covering millions of homes across more than ten markets as of early 2026, with continued expansion underway.
- Spectrum, Cox, Mediacom, and Cable One (Sparklight) are actively upgrading, but broad DOCSIS 4.0 availability for most of their customers is more likely in late 2026 through 2027.
- Optimum (Altice) is taking a different path, sticking with DOCSIS 3.1 upgrades on its cable network while expanding fiber rather than rolling out DOCSIS 4.0.
Jump to Your ISP
What DOCSIS 4.0 Is, in Plain English
DOCSIS 4.0 is the newest version of the technology that lets cable internet travel over the coaxial cable already wired into most American homes. The big change is upload speed. For decades, cable internet has offered fast downloads but slow uploads. DOCSIS 4.0 supports up to 10 Gbps download and 6 Gbps upload, which finally lets cable compete with fiber on the upstream side. For everyday users that means smoother video calls, faster cloud backups, better gaming, and less buffering when many devices are connected at once.
You do not need a new cable line for DOCSIS 4.0. Your provider has to upgrade the equipment in their network and the modem or gateway in your home. Until both are in place, you will still be on DOCSIS 3.1, which is the current standard for almost all cable customers today.
For a deeper explainer, see our full DOCSIS 4.0 speeds and timeline guide and our DOCSIS 3.1 vs DOCSIS 4.0 comparison.
Comcast Xfinity DOCSIS 4.0 Rollout
Status: Live and expanding to millions of homes
Comcast launched the first commercial DOCSIS 4.0 service in the world in late 2023, starting in Colorado Springs, Atlanta, and Philadelphia. The service is sold under the X-Class Internet brand and offers symmetrical speed tiers up to 2 Gbps, with plans to push tiers higher over time.
By late 2024, Comcast had expanded to about ten markets covering roughly one million homes. As of early 2026, Comcast says DOCSIS 4.0 is no longer concentrated in a few cities and now reaches millions of homes across its footprint. Known active markets include Atlanta, Philadelphia, Colorado Springs, Sacramento, Denver, Seattle, Augusta, Miami, and Pittsburgh, with more being added regularly.
To check availability at your address, log in to your Xfinity account and look for X-Class Internet tiers, or call Xfinity and ask whether DOCSIS 4.0 is available in your neighborhood.
Charter Spectrum DOCSIS 4.0 Rollout
Status: Network upgrades in progress, full deployment running into 2027
Charter announced its DOCSIS 4.0 plan in late 2022 with an original target of 2025. That date has slipped twice. As of late 2024, Charter said its full network evolution project would not be complete until 2027, citing equipment certification delays.
Charter is pursuing Extended Spectrum DOCSIS (ESD) rather than the Full Duplex (FDX) version that Comcast uses. As a Spectrum customer, the practical difference is invisible. Both options deliver the same headline speed improvements.
The first phase, which covers high-split upgrades and faster upload speeds, is already complete across part of Charter's footprint. The remaining phases will continue rolling out through 2026 and into 2027.
Charter has also proposed a merger with Cox Communications. If the deal closes in the second half of 2026 as expected, Charter has signaled it will accelerate DOCSIS 4.0 upgrades in Cox markets.
Cox Communications DOCSIS 4.0 Rollout
Status: Lab-tested, limited deployments starting, broader rollout in 2026 and beyond
Cox has taken a deliberately cautious approach, prioritizing reliability over speed-to-market. Cox is using the Extended Spectrum (ESD) version of DOCSIS 4.0, with limited deployments beginning and full-scale rollouts expected during 2026.
The Cox-Charter merger is the biggest variable for Cox subscribers. If the merger is approved, the timeline could shift significantly, with Charter committing to accelerate DOCSIS 4.0 in Cox markets.
For now, most Cox customers should plan on remaining on DOCSIS 3.1 through 2026. Cox has been actively pushing subscribers off older DOCSIS 3.0 modems, which is a separate upgrade you may want to make regardless of when DOCSIS 4.0 arrives.
Mediacom DOCSIS 4.0 Rollout
Status: Commercially deployed in select markets, expanding to one million homes by end of 2026
Mediacom launched its first commercial DOCSIS 4.0 service in Moline, Illinois in September 2025. Mediacom is using the ESD flavor of DOCSIS 4.0 with a 1.8 GHz plant capacity and an ultra-high split that dedicates a large block of spectrum to upload traffic.
Mediacom has committed to bringing multi-gig speeds to roughly one million homes by the end of 2026 across its three-million-home footprint, and the operator says expansion beyond that is likely. Early upgrade markets include parts of Iowa (Cedar Rapids, Des Moines, West Des Moines) and smaller systems in Kentucky and Minnesota.
Sparklight (Cable One) DOCSIS 4.0 Rollout
Status: Network preparation underway, rollout ramping through 2026 and 2027
Sparklight, the consumer brand of Cable One, has been preparing its network for DOCSIS 4.0 for several years. The company is pursuing the Extended Spectrum (ESD) version, with plans to upgrade plant capacity to 1.8 GHz, push fiber deeper into neighborhoods, and reclaim spectrum used by traditional cable TV.
Cable One operates several brands including Sparklight, Fidelity Communications, Hargray, and ValuNet Fiber, covering more than one million customers across 24 states. Multi-gig service has launched in select Hargray and Sparklight markets such as Lake Oconee, Georgia, and the broader DOCSIS 4.0 rollout will continue through 2026 and into 2027.
Sparklight has been requiring new customers to use DOCSIS 3.1 modems for some time, which means your equipment will already be ready for the upgrade in most cases. You can check the official Sparklight supported modems list for current details.
Optimum (Altice USA) DOCSIS 4.0 Rollout
Status: Not pursuing DOCSIS 4.0. Upgrading DOCSIS 3.1 and expanding fiber instead
Optimum is the only major U.S. cable ISP that has publicly opted out of DOCSIS 4.0. CEO Dennis Mathew has said Altice does not plan to pursue DOCSIS 4.0 upgrades. Instead, the company is using mid-split DOCSIS 3.1 upgrades to deliver multi-gig downloads on cable and pushing fiber-to-the-home into more of its footprint.
Altice's stated goal is to offer multi-gig speeds to 65% of its footprint by 2028, using a combination of DOCSIS 3.1 cable and fiber. On the fiber side, Optimum already offers symmetrical speeds up to 8 Gbps in some markets.
The bottom line for Optimum customers: if you want true symmetrical multi-gig service, your path is fiber. If fiber is not available at your address, you will be on a DOCSIS 3.1 cable plan for the foreseeable future.
Astound Broadband DOCSIS 4.0 Rollout
Status: Evaluating DOCSIS 4.0 and fiber market by market
Astound Broadband (which includes the former RCN, Grande Communications, and Wave Broadband) is upgrading its network using Harmonic equipment and is evaluating DOCSIS 4.0 and fiber on a market-by-market basis. Astound already offers symmetrical 5 Gbps fiber service in some areas. The cable side is moving toward DOCSIS 4.0 capability through a virtualized cable modem termination system and distributed access architecture.
No specific DOCSIS 4.0 launch dates have been published. Expect gradual rollout starting in 2026 and 2027, with priority on markets facing the strongest fiber competition.
WOW! Internet DOCSIS 4.0 Rollout
Status: Focused on fiber expansion, no formal DOCSIS 4.0 timeline announced
WOW! is taking a fiber-first approach in most of its newer expansion markets, including Central Florida, Greenville, South Carolina, and parts of Michigan, where it is building fiber-to-the-home networks with speeds up to 5 Gbps. WOW! has not announced a specific DOCSIS 4.0 deployment schedule for its existing cable footprint. Customers in legacy cable markets should plan on DOCSIS 3.1 through 2026 and beyond.
Midco DOCSIS 4.0 Rollout
Status: Upgrading network and expanding fiber, DOCSIS 4.0 timeline not yet public
Midco serves more than 400 communities across Minnesota, North Dakota, South Dakota, Wisconsin, and Kansas. The company has been actively investing in fiber, reaching more than 100,000 fiber premises in 2024, and has signaled DOCSIS 4.0 is part of its longer-term roadmap. No firm consumer launch dates have been announced. Expect continued DOCSIS 3.1 service across most Midco markets through 2026.
Breezeline DOCSIS 4.0 Rollout
Status: No public DOCSIS 4.0 commitment yet
Breezeline (formerly Atlantic Broadband) serves customers in 13 states across the Northeast, Mid-Atlantic, South, and Midwest. The company has not announced specific DOCSIS 4.0 deployment plans. Most Breezeline customers will remain on DOCSIS 3.1 in the near term. Multi-gig fiber is available in select Breezeline markets.
Buckeye Broadband DOCSIS 4.0 Rollout
Status: Multi-gig service available, no DOCSIS 4.0 announcement
Toledo-based Buckeye Broadband offers cable internet up to 10 Gig in select areas of Northwest Ohio and Southeast Michigan, largely via fiber expansion. Buckeye has not made a public DOCSIS 4.0 commitment. Existing customers should expect DOCSIS 3.1 service for now.
GCI (Alaska) DOCSIS 4.0 Rollout
Status: Multi-gig service via DOCSIS 3.1 and fiber, no DOCSIS 4.0 timeline announced
GCI, Alaska's largest cable provider, delivers up to 2.5 Gbps service in Anchorage and other markets primarily through DOCSIS 3.1 and fiber upgrades. No formal DOCSIS 4.0 launch has been announced.
Smaller and Local Cable ISPs
Dozens of smaller cable operators serve specific cities, counties, or rural regions across the United States. Examples include Blue Ridge Communications (Pennsylvania), Service Electric (Pennsylvania and New Jersey), Armstrong (Pennsylvania, Ohio, Maryland, West Virginia, Kentucky, New York), TDS Telecom cable systems, Cogeco (in Canada), Vyve Broadband, and many municipal or co-op operators.
Most small operators are not building their own DOCSIS 4.0 deployments. They typically follow once vendor equipment becomes plentiful, prices come down, and certification testing has been worked out by the larger ISPs. Realistically, expect most small cable providers to consider DOCSIS 4.0 starting in 2027 and beyond, if at all. Many small operators are choosing to build fiber-to-the-home instead, which provides similar consumer-facing speeds without the complexity of upgrading the entire cable plant.
If you are on a small or local cable ISP, the most reliable way to check status is to call customer service and ask two questions: "Do you support DOCSIS 4.0 at my address?" and "What is the highest speed plan available to me right now?"
Why the DOCSIS 4.0 Rollout Is Taking So Long
Three things have slowed the timeline. First, DOCSIS 4.0 requires upgrades all the way down the network, from the headend out to the amplifiers and into the home. That is a major capital project. Second, two competing approaches (Full Duplex DOCSIS and Extended Spectrum DOCSIS) meant vendors had to develop and certify multiple chipsets. Third, certification and interoperability testing between modems, nodes, and cable modem termination systems has taken longer than operators originally hoped.
The good news is that new "unified" silicon from Broadcom now supports both FDX and ESD on the same hardware, which is allowing larger operators (Comcast in particular) to scale up faster in 2026.
What You Should Do Right Now
If you are on DOCSIS 3.0, upgrade to a DOCSIS 3.1 modem now. DOCSIS 3.0 caps you below gigabit speeds and most major ISPs are phasing it out. A DOCSIS 3.1 modem with a 2.5 Gbps Ethernet port will support every cable plan currently sold, including multi-gig tiers, and will keep working as your ISP rolls out DOCSIS 4.0 on the network side.
If you are already on DOCSIS 3.1, sit tight. Retail DOCSIS 4.0 modems are expected to begin appearing in mid-to-late 2026, with pricing likely starting around $150 to $250. Unless your ISP has already activated DOCSIS 4.0 at your address, there is no benefit to buying a DOCSIS 4.0 modem yet. For specific recommendations, see our Xfinity-compatible modem list and full modem catalog.
Frequently Asked Questions
How do I know if DOCSIS 4.0 is available at my address?
The most reliable way is to check directly with your ISP. For Xfinity customers, log in to your account and look for X-Class Internet tiers (300, 500, 1 Gig, 2 Gig symmetrical) or call to ask if your address is in a DOCSIS 4.0 market. For other ISPs, call customer service and ask whether DOCSIS 4.0 or multi-gig symmetrical service is available at your specific address.
Do I need a new modem for DOCSIS 4.0?
Yes. A DOCSIS 4.0 service requires a DOCSIS 4.0 modem or gateway. Right now, most DOCSIS 4.0 modems are issued by ISPs (such as the Comcast XB10 gateway). Retail DOCSIS 4.0 modems from brands like ARRIS, Motorola, NETGEAR, and Hitron are expected to appear in stores in mid-to-late 2026.
Is DOCSIS 4.0 better than fiber?
Fiber generally offers a slight edge in maximum upload speed (up to 10 Gbps symmetrical) and latency, but DOCSIS 4.0 closes the gap dramatically. For most home users, a multi-gig DOCSIS 4.0 connection will feel identical to a comparable fiber connection. The bigger advantage of DOCSIS 4.0 is that it runs on the existing coaxial wiring in your home, so cable companies can offer multi-gig service without digging new lines.
Will my current DOCSIS 3.1 modem still work after my ISP launches DOCSIS 4.0?
Yes. DOCSIS is backward compatible. A DOCSIS 3.1 modem will continue to work on a DOCSIS 4.0 network, but it will not deliver the new symmetrical multi-gig speeds. You will only see the full benefit of DOCSIS 4.0 once you also upgrade your modem.
What is the difference between Full Duplex (FDX) and Extended Spectrum (ESD) DOCSIS 4.0?
Both are flavors of DOCSIS 4.0 that deliver similar speed improvements to home users. FDX lets upload and download traffic share the same block of cable spectrum, and is the approach Comcast is using. ESD expands the total spectrum on the cable to 1.8 GHz and keeps upload and download in separate bands. Charter, Cox, Mediacom, and Cable One are pursuing ESD. As a customer, you do not need to choose. Your ISP picks the technology.
Why is Optimum not rolling out DOCSIS 4.0?
Optimum's parent company Altice USA has decided to keep its cable network on DOCSIS 3.1 and invest in fiber-to-the-home instead. If you want symmetrical multi-gig service from Optimum, your only path is fiber. Optimum offers fiber plans up to 8 Gbps symmetrical in markets where it has built out fiber infrastructure.
When will small local cable companies get DOCSIS 4.0?
Most small and regional cable ISPs are waiting for vendor equipment to become widely available and certified before committing to DOCSIS 4.0. Realistically, expect 2027 or later for most smaller operators, and many will choose to deploy fiber-to-the-home instead. Call your provider directly for the most current information about your specific service area.
Will DOCSIS 4.0 raise my internet bill?
Not automatically. You can stay on your current plan even after DOCSIS 4.0 launches in your area. You only pay more if you choose to upgrade to a higher-tier plan that uses the new capacity. Comcast's entry-level DOCSIS 4.0 plan (X-Class 300 Mbps) is priced similarly to comparable DOCSIS 3.1 plans, with higher tiers costing more.
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