@tuxy I own a Pixel 3a and an Lg Nexus 4. They are all running Ubutntu Touch (which I love). However, you will only be able to make phone calls by utilizing Linphone and Sip (as someone else mentioned). Until Ubuntu Touch is able to support Volte (Voice over Long Term Evolution), you will not be able to make phone calls by connecting to one of the USA networks. A few may still be working, but by July, 2022 they will all be gone. So let us all pray for Volte implementation in Ubuntu Touch. They are working on it, but it is evidently a really difficult implementation to develop.