Calls fail but data works (and the reverse): what’s actually broken

The failure matrix

Why calls are now the fragile part

For years, calls were the thing that always worked — they traveled on dedicated 2G/3G circuits while data was the temperamental add-on. The major U.S. carriers shut those legacy networks down in 2022, and voice moved onto the data network as VoLTE. The practical consequence: a phone or plan with broken VoLTE provisioning can have perfect data and no ability to place a call. It’s common after switching carriers with an older or imported phone (the new network’s VoLTE profile isn’t there — closely related to band mismatch), after OS updates that reset network settings — including an update that reset your IMS entitlement — and on devices where VoLTE was manually disabled back when it was optional.

The reverse case: data dead, calls fine

Work through it in this order — it’s sorted by how often each is the cause: the boring toggles (mobile data off, data roaming off while technically roaming, a data limit or focus mode blocking apps), the plan (high-speed allowance exhausted and reduced to a crawl, or a prepaid data pass expired), and only then APN settings — the carrier-specific configuration your phone uses to reach the data network. Carrier-settings updates fix APNs automatically on most phones; Android additionally lets you reset APNs to default manually. If you’ve BYOD’d onto an MVNO, use the APN values your brand publishes, not the host carrier’s.