Spectrum Mobile & Apple products

Since trying to switch to Spectrum Mobile from AT&T about a week ago, I’ve been left without voice phone service. When I tried to get hooked up with Spectrum, I learned that my iPhone XS Max was one of the few Apple phones that was not compatible with their system. So I get a new SIM (eSIM) card and installed it, but it seems I have even more hoops to jump through. All is well with my iPhone, except I still have no voice service. HELP! I need that phone working! Any ideas, anyone?