technology
VoLTE (Voice over LTE)
The technology that carries voice calls over 4G — and the certification a phone must have to place calls on modern US networks.
VoLTE (Voice over LTE) carries phone calls as data over the 4G network. Since US carriers shut down their 2G and 3G networks, VoLTE is the only way a phone can place calls — which makes it the single most important compatibility check when buying a dumbphone.
The catch: it is not enough for a phone to "support 4G." The device must be VoLTE-certified for your specific carrier — Verizon keeps a strict device allowlist, AT&T maintains a whitelist by model number, and T-Mobile is the most permissive. An uncertified phone may show signal bars yet fail to place a single call.
Related Terms
View all →Feature phone
The industry term for keypad phones with basic capabilities — the hardware category most dumbphones belong to.
KaiOS
A lightweight operating system for keypad phones that adds a small curated app layer — WhatsApp, Google Maps — to feature phones.
MVNO (virtual carrier)
A low-cost carrier that rents capacity from the big networks — often the cheapest way to run a dumbphone.