In the US there are really only three nationwide networks — Verizon, AT&T, and T-Mobile — plus Boost's newer network. Almost every other “carrier” you've heard of is an MVNO: a smaller brand that rents coverage from one of those three. Knowing which network your carrier actually uses tells you exactly what coverage you'll get and whether your phone will work.
The carrier-to-network map
- Verizon network: Verizon, Visible, Total Wireless, Twigby, Spectrum Mobile, Xfinity Mobile, Straight Talk.
- AT&T network: AT&T, Cricket, Red Pocket (AT&T SIM), H2O, Straight Talk (some SIMs).
- T-Mobile network: T-Mobile, Mint Mobile, Metro by T-Mobile, Ultra Mobile, Google Fi (primarily).
- Multi-network (you choose): US Mobile, Red Pocket, TracFone, Straight Talk.
- Boost Mobile: AT&T's network since November 2025, when Boost shut down its own towers, with access to T-Mobile too.
GSM vs CDMA: mostly obsolete
You'll still see “is this carrier GSM or CDMA?” everywhere. The honest version: GSM and CDMA were competing 3G technologies (AT&T/T-Mobile were GSM; Verizon and old Sprint were CDMA), and a decade ago a phone built for one wouldn't work on the other. Today it barely matters — modern 4G LTE and 5G are a single global standard, and the old 3G networks are shut down. What determines compatibility now is VoLTE support and band coverage, not GSM-vs-CDMA.
Why the network matters before you switch
- Coverage: an MVNO uses the same towers as its host. If Verizon works great at your house, Visible will too — for far less. If T-Mobile is weak where you live, avoid T-Mobile MVNOs.
- Your phone: a phone optimized for one network may miss bands for another. Most modern unlocked phones work across all three, but it's worth an IMEI check first.
Once you know which network covers you, compare the value carriers riding it.
Best MVNO phone plans →Bottom line
It comes down to a simple rule: three big networks — Verizon, AT&T, T-Mobile — plus Boost's own, and nearly every other brand is an MVNO renting one of them. Match the network to where you live, then pick the cheapest MVNO on it, and you get the same coverage for far less.
Frequently asked questions
How do I know what network my carrier uses? +
Does GSM vs CDMA still matter? +
Do MVNOs have worse coverage than the big carriers? +
Which network has the best coverage? +
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Jean writes ShopCellPlans' reviews. He compares carrier plans using each carrier's own published prices, its FCC broadband labels and reporting from named outlets, and ranks them on the bill you actually get, taxes and fees included, not the price on the ad.