T-Mobile Business Internet vs. Comcast Business: which costs less?
Both now sell business internet with a 5-year price lock. They get there differently: T-Mobile over 5G with no contract, Comcast over cable with a 1-year agreement. Here's what each costs over three years and what the guarantees leave out.
T-Mobile costs far less over three years: $1,260 on Small Business Grow with a voice line, against about $5,000 for Comcast Business 300 Mbps with its 5-Year Price Lock and modem. Comcast gives you a wired line with steadier speeds, faster uploads where it has upgraded, and an SLA option on dedicated fiber. If outages would stop sales, use Comcast as the main line and T-Mobile as backup.
What you pay over three years
Cable providers usually advertise a first-year price that rises when the promotion ends, so compare the total over the time you expect to stay. T-Mobile's price is fixed for five years on every plan. Comcast offers a choice: one-year pricing that moves to a standard rate in year two, or a 5-Year Price Lock for $40 a month more.
Internet only, before taxes and fees, from T-Mobile and Comcast Business plan pages and Comcast's broadband labels, checked Oct 2026. T-Mobile's $35 and $50 prices need a T-Mobile business voice line, billed separately, and AutoPay; there's a $35 device connection charge at sign-up. Comcast prices need bank AutoPay and paperless billing on a 1-year agreement; the modem is $27.95/mo on 300 and 500 Mbps unless you bring your own, and professional installation is $129.95.
Where T-Mobile wins
Price and speed of setup. The gateway ships in two days and plugs in, there's no contract, and T-Mobile pays up to $800 toward your old provider's termination or switching costs. Data is unlimited. It suits shops, restaurants, pop-ups and small offices with a strong 5G signal, and it's one of the cheapest failover lines you can add behind a wired connection.
The tradeoffs come from running over a shared cellular network. Speeds change with signal and tower load, business traffic can be slowed during congestion, and T-Mobile doesn't publish an uptime SLA for these plans. SuperBroadband, which pairs T-Mobile 5G with Starlink, includes a 99.99% uptime guarantee: a credit of 20% of the base monthly price for an outage of 4.3 minutes or more, claimed within 14 days. It needs both T-Mobile 5G and Starlink coverage at your address and may require a contract.
Where Comcast wins
Comcast Business reaches more business addresses than any other provider, and a wired line doesn't depend on the signal at your window. Plans run to 2 Gbps, with uploads up to 300 Mbps where Comcast has upgraded the line. Static IPs come in blocks of 1, 5 or 13, and every plan includes SecurityEdge network protection. If you need an uptime guarantee, Comcast sells dedicated internet with an SLA.
Check the upload speed at your address before you sign: older lines are limited to 35 Mbps up, which is tight for video calls and cloud backups. See static IPs and SLAs if you're not sure you need either.
What the price guarantees leave out
T-Mobile's 5-Year Price Guarantee covers the price of the 5G internet data on an eligible plan. It doesn't cover:
- →Taxes and fees
- →Equipment or speed upgrades you choose
- →Future wireless generations, limited-time promotions and per-use charges
- →The voice-line bill credit: drop the voice line or change plans and the $35 price goes up
Comcast's 5-Year Price Lock keeps the plan rate for 60 months, but it costs $40 a month more than one-year pricing and still comes with a 1-year agreement. The modem fee on 300 and 500 Mbps is separate. Read the full terms at sign-up for both.
Test T-Mobile before you switch
- →Check T-Mobile's business coverage map at your exact address.
- →Run speed tests in the morning, at lunch and in late afternoon over a few business days.
- →Make a video call and a VoIP call at peak times and watch for drops.
- →Keep your Comcast line active until you're happy with the results.
Which should you get?
Choose T-Mobile if you're a small team with a strong 5G signal, mostly cloud apps and card payments, and you want the lowest fixed price. Choose Comcast if you upload a lot, run several video calls at once, need static IPs, or can't afford slowdowns at busy times. If downtime costs you sales, run both: Comcast as the main line and T-Mobile Small Business Internet Backup at $20 a month, with a UPS to keep the equipment on in a power cut. If business fiber reaches your building, compare AT&T Business Fiber first.
Jean founded ShopHighSpeed after trying to find one straight answer about business internet in his own town. He has been a Comcast and Verizon Fios customer, and ranks providers on what they actually deliver, not on what they advertise.
Sources (2)
- Plan pages, offer terms and Broadband Facts labels from T-Mobile Business Internet and Comcast Business, checked Oct 2026
- T-Mobile 5-Year Price Guarantee and SuperBroadband uptime guarantee terms, checked Oct 2026
Prices and offers change often; confirm at your address before you order. How we research
Questions
Is T-Mobile Business Internet cheaper than Comcast Business?
Usually, over three years. T-Mobile Small Business Grow is $35 a month with a T-Mobile business voice line, about $1,260 over 36 months. Comcast Business 300 Mbps is $70 a month for the first year, then a standard rate of $149.95, plus a $27.95 modem unless you bring your own.
Does T-Mobile Business Internet have an uptime SLA?
Not on standard plans. T-Mobile SuperBroadband, which adds Starlink as a second connection, includes a 99.99% uptime guarantee paid as a 20% bill credit. Comcast offers contractual SLAs on Comcast Business Dedicated Internet, sold by quote.
Which has faster uploads?
It depends on the address. Comcast Business uploads range from 35 Mbps on older lines to 300 Mbps on upgraded ones, and symmetrical on its newest connections. T-Mobile 5G speeds depend on signal and tower load.
Can I use both?
Yes. Many businesses run Comcast Business as the main line and T-Mobile Small Business Internet Backup, $20 a month, as failover.
