Quantum Fiber (now AT&T Fiber) vs. Xfinity
AT&T bought Quantum Fiber on Feb 2, 2026, and Quantum customers are moving to AT&T Fiber. Here's how that service compares with Xfinity.
Fiber wins on speed: equal upload and download, and AT&T Fiber 300 is $50/mo with no data cap. Xfinity is $45 for 300 Mbps with a 5-year price guarantee but uploads top out at 100 Mbps on most plans. Former Quantum customers should check which AT&T plan they're moving to.
Side by side
If you were a Quantum customer
- Your service continues; AT&T is moving Quantum customers to AT&T Fiber.
- Ask AT&T which plan and price you'll move to, in writing.
- Check AT&T's 20% off with an eligible AT&T unlimited wireless plan.
- See what replaced CenturyLink.
Which to choose
Choose fiber for working from home, large uploads and gaming. Choose Xfinity if fiber isn't at your address or you value the 5-year guarantee most. Reviews: AT&T Fiber · Quantum · Xfinity.
What it costs over three years
At 1 Gig the cost is about even, and fiber gives you equal upload speed.
Who each suits
- Fiber: remote workers, gamers, anyone uploading large files or backing up to the cloud.
- Xfinity: households that mostly stream and want a published 5-year price guarantee, or where fiber isn't available.
- Either: check the price after any promotion and whether equipment is included.
Setup
- AT&T Fiber: professional installation, gateway included.
- Xfinity: self-install kit if your home has an active cable line, or a technician; the gateway is included on the current plans.
Questions
Is Quantum Fiber still available?
Quantum Fiber is now part of AT&T, which bought it on Feb 2, 2026. Quantum customers are moving to AT&T Fiber.
Is fiber better than Xfinity cable?
Fiber has equal upload and download speeds and holds up better at busy times. Xfinity's cable uploads top out at 100 Mbps on most plans.
Who bought Quantum Fiber?
AT&T, on Feb 2, 2026. Quantum was previously owned by Lumen, CenturyLink's parent company.
Will my Quantum Fiber price change under AT&T?
Ask AT&T which plan you're moving to and get the price in writing. AT&T Fiber 1 Gig is $70/mo with AutoPay and paperless billing.
Sources (2)
- Plan pages and Broadband Facts labels from AT&T Fiber, Quantum Fiber, Xfinity, checked Oct 2026
- Company press releases and regulatory filings on the ownership changes mentioned
Prices and offers change often; confirm at your address before you order. How we research
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.