My Mobian CE 3Gb also does not receive SMS. I’m using Google Fi in the USA.
CORRECTION: I was not receiving SMS because I was sending from an iPhone and my Apple account had previously allowed Apple's non-SMS Message method. So, it was going to iOS devices but not via SMS. I turned that off in my Apple account and now my PinePhone receives SMS.
CORRECTION: I was not receiving SMS because I was sending from an iPhone and my Apple account had previously allowed Apple's non-SMS Message method. So, it was going to iOS devices but not via SMS. I turned that off in my Apple account and now my PinePhone receives SMS.