In LTE and 5G there exists no cellular signal without data. That was a 2G/3G thing. Since 4G everything is data. The separate sms and voice services are gone. And 3G is rapidly being deprecated.
replyThat's not quite true. VoLTE was an optional part of 4G in the beginning. I had one of the gaming ASUS phones that shipped with 4G, but no VoLTE. 6 months after getting it, the US phone carriers conspired to make VoLTE mandatory for connecting to their towers, effectively bricking my device. ASUS never issued the firmware update that would have enabled the feature in the modem, which had the capability, and the community hack to enable it never worked for me.
replyYes, circuit switched fallback was possible for a time (LTE data and circuit-switched 2G or 3G voice). I think 3GPP shouldn't have written that into the spec in the first place, but you know what they say about hindsight....
replyThe whole saga with VoLTE was really quite entertaining: https://nickvsnetworking.com/background-to-the-volte-mess/
4G without VoLTE is using 3G for voice because there is no other 4G voice.
replyIt's true that it's all packet-switched rather than circuit-switched, but IMS traffic is still handled differently than regular data traffic. (The most user-visible implication of this is the QCI difference: cellular phone calls are much more reliable at poor signal strength and high congestion than over-the-top VoIP calls).
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