The two largest MVNOs in the United States are not mobile companies. Spectrum Mobile ended June 2026 with 12.5 million lines and Xfinity Mobile with 10.2 million, and between them, Optimum Mobile and a handful of smaller cable brands, the cable industry now takes more than a third of the country’s smartphone net adds in a typical quarter. Every one of those lines rides a wholesale agreement with Verizon or T-Mobile. Here is how the cable MVNO model works, what it has become, and why it matters to everyone else in the wholesale market.
The scoreboard, Q2 2026
| Brand (parent) | Lines, June 30 2026 | Q2 net adds | Host network |
|---|---|---|---|
| Spectrum Mobile (Charter) | 12.5 million | +406,000 | Verizon (consumer); T-Mobile (business) |
| Xfinity Mobile (Comcast) | 10.19 million | +448,000 (record) | Verizon (consumer); T-Mobile (business) |
| Optimum Mobile (Altice USA) | 724,000 | +49,900 | T-Mobile |
| Cox Mobile (now Charter) | not disclosed | — | Verizon |
| Astound Mobile | not disclosed | — | T-Mobile (via Reach) |
The growth is not slowing. Charter added 1.7 million lines over the twelve months to June, 16% growth, in a quarter where it lost 172,000 internet customers. Comcast’s 448,000 adds were its best on record while its broadband base shrank by 167,000. Mobile service revenue at Charter reached $1.1 billion for the quarter, up 18.9%; Comcast booked just over $1 billion in wireless service plus $404 million in device revenue. Optimum, the smallest of the three public reporters, grew mobile service revenue 40% year on year and pushed penetration of its broadband base from 6.9% to 8.9%.
The scale is easy to underrate. MoffettNathanson calculated that cable took 39% of US smartphone net adds and 17% of postpaid gross adds in the third quarter of 2025, more than T-Mobile’s 31%, Verizon’s 28% or AT&T’s 24% share of net adds, and expected cable’s share to “rise dramatically” through 2026. Comcast’s own framing on its Q2 call was that 10.2 million lines is 17% of its residential broadband base but “only 7% penetration of the total wireless line opportunity” in its footprint.
How the Verizon deals work
Charter and Comcast both sell mobile on Verizon’s network under agreements that trace back to a 2011 spectrum sale and were substantially renegotiated in 2022. Comcast’s CEO described the renegotiated deal as running “in perpetuity,” and the key provision, for anyone studying these contracts, is that it explicitly allows Comcast to offload traffic to its own CBRS radios and “become a hybrid MNO.” Charter’s agreement mirrors it; the two companies share “one technology roadmap to interface with Verizon.”
That offload right is the economic engine. Charter reports that 88% of Spectrum Mobile traffic already rides infrastructure it controls, mostly Wi-Fi, and targets moving 30% of total traffic onto its own CBRS small cells. At roughly $2,500 per strand-mounted CBRS radio, against $20,000 to $50,000 for a conventional small cell, Charter puts the payback at “well under a year” and the prize at about $530 million a year in avoided wholesale payments; it had CBRS live in 23 markets at the end of 2025 and expects offload to reach “the low 90s” percent. Comcast reports around 90% Wi-Fi offload and has CBRS deployed at smaller scale. Together the two companies spent $922 million on CBRS priority access licenses.
In January 2026 both companies announced “modernized” agreements with Verizon. Analyst Roger Entner’s read is that they “got a better rate,” and that the leverage came from elsewhere.
The T-Mobile business deal
On July 22, 2025, Charter and Comcast signed a multi-year, exclusive MVNO agreement with T-Mobile for business customers, sold as Spectrum Mobile for Business and Comcast Business Mobile from 2026. Financial terms were not disclosed. The practical difference is scale per account: the T-Mobile arrangement supports up to 1,000 lines per small or mid-sized business, where the Verizon consumer deal had capped business accounts around 20 lines. Both operators confirmed on their Q2 2026 calls that the T-Mobile service is live, and Charter noted it is “principally on the residential side” with Verizon now. For the first time the two largest MVNOs in the country are dual-sourced, which is exactly the position a wholesale buyer wants to be in when the next rate discussion comes around.
Charter plus Cox
Charter’s $34.5 billion enterprise-value acquisition of Cox Communications closed on August 20, 2026, creating an operator passing about 70 million homes and businesses in 45 states. Cox Mobile, which launched nationally in January 2023 on Verizon and never disclosed line counts, folds into Spectrum Mobile; the Spectrum brand rolls into Cox markets within about a month, with the full product launch expected in mid-September. Cox internet customers are being offered a free mobile line for a year unless they already had Cox Mobile, which is the same playbook that produced Charter’s growth curve. Roughly half of Comcast’s recent postpaid connects took a free line too. Give the line away, then upsell the second and third.
Why this matters to the wholesale market
Cable is the proof that a virtual operator can win share from the facilities-based carriers at scale, and the terms it negotiated are the template every other large MVNO now asks for: perpetual agreements, offload rights, dual sourcing. It also sets the ceiling on how far a host carrier will go. When asked whether Starlink could reach customers through cable’s MVNO deals, Verizon’s CEO Dan Schulman was unambiguous: “There is no backdoor to our MVNOs in any structure.” For the smaller MVNO, the lesson is that wholesale rates are negotiable when you bring your own offload and your own distribution, and not otherwise. For the enablers and aggregators serving the next tier of cable operators through NCTC, the lesson is that the demand is real: the big three have shown independent ISPs what mobile does to churn, and the smaller ones are now lining up to copy it.
Coverage of cable mobile lives in our Cable MVNOs section. Vendors serving cable and ISP mobile launches are in the directory.
Frequently Asked Questions
How many subscribers do the cable MVNOs have?
As of June 30, 2026, Spectrum Mobile (Charter) reported 12.5 million lines and Xfinity Mobile (Comcast) 10.19 million. Optimum Mobile (Altice USA) had 724,000. Cox Mobile, now part of Charter, and Astound Mobile have not disclosed line counts.
Which network do Spectrum Mobile and Xfinity Mobile use?
Both run consumer service on Verizon’s network under long-term MVNO agreements that allow them to offload traffic to their own Wi-Fi and CBRS radios. For business customers, both launched service on T-Mobile in 2026 under a separate multi-year agreement signed in July 2025. Optimum Mobile uses T-Mobile.
Why are cable companies so successful at selling mobile?
They bundle mobile with broadband they already sell to the household, frequently give the first line away free, and offload roughly 90% of traffic to Wi-Fi and CBRS small cells, which keeps wholesale costs low. Cable took about 39% of US smartphone net adds in the third quarter of 2025 according to MoffettNathanson.
What happened to Cox Mobile after the Charter merger?
Charter closed its acquisition of Cox Communications on August 20, 2026. Cox Mobile customers move to Spectrum Mobile, the Spectrum brand rolls out in Cox markets within about a month, and Cox internet customers are being offered a free mobile line for one year unless they already had Cox Mobile.
Sources
Charter Q2 2026 results · Comcast Q2 2026 results · Optimum Q2 2026 results · Charter Q2 2026 call transcript · Comcast Q2 2026 call transcript · Fierce: Comcast–Verizon deal and CBRS offload · Light Reading: modernized Verizon pacts · Light Reading: CBRS build-out · T-Mobile: Charter and Comcast business agreement · Charter–Cox announcement · Fierce: Charter closes Cox · Fierce: Cox Mobile launch · Fierce: Altice–T-Mobile extension · Light Reading: MoffettNathanson on cable share · Fierce: Verizon CEO on Starlink