Well yeah. Usually the "smart" in smartphone refers to the application processor and user facing OS. I don't think you can connect to an LTE network without a

Well yeah. Usually the "smart" in smartphone refers to the application processor and user facing OS. I don't think you can connect to an LTE network without a baseband processor. If your threat model includes the firmware on the baseband processor, best not to use a smartphone at all. Or leave your cave in the mountains of Pakistan.