I'm not sure this is the right section, I apologize in advance. I'm from Italy, we recently had some issue using an italian SIM card (only-data SIM card, provider is WIND Tre) which is supposed to work off the shelf in roaming with AT&T in US. We used an industrial professional router (Digi IX20) and everything was working here in Italy, but then in US we got "No signal" and weren't able to use that at all. Router manufacturer claims that in order to work with US networks, the device IMEI has to be registered.. is that true? Why this don't apply to phones? Who take care of this registration?
Router model is specifically this and roaming is enabled.