Running HAOS on an x86 - could anyone recommend a USB-modem that would work? Needs to be 4g or 5g.
Having a hard time finding anything here in Norway 
For reference, I got a Teltonika TRM240, seems to work fine.
It works, but if you are in the US the hardware advice has changed — worth knowing before committing to a modem.
2G is gone. T-Mobile completed its shutdown on 2 August 2026; AT&T and Verizon years earlier. The SIM800L/SIM800C modules most guides recommend now register nowhere in the US. Older LTE dongles without an IMS/VoLTE stack (Huawei E3372 and similar) also stopped sending, because their SMS rode the circuit-switched core that was retired alongside 2G — LTE data keeps working, so they look perfectly healthy while sending nothing at all.
A modern LTE module needs one patch. A SIMCom SIM7670G registers and receives fine, but every send fails with TIMEOUT[14]. That turned out to be a libGammu bug rather than the modem: it only accepts an SMS prompt of "> ", and the module emits a bare ">". Reported and fixed upstream in at: accept SMS prompt sent as a bare ">" without trailing space by ocalvo · Pull Request #1177 · gammu/gammu · GitHub.
So the integration is still perfectly usable here — it just needs LTE hardware and, for now, a patched libGammu.
Full write-up with the byte-level detail and debugging notes: