Hope I don't step over boundaries here, but translated OPs post with Google translate:
' Good morning there is a user who speaks Spanish, I have a pixel 8a with android 15c I have installed grapheneos, everything ok, but when I make calls it lets me, however it does not let me receive them, change sim for that of another operator; the same problem, the operators are Jazztel and Butik, I contacted by x with the grapheneos team they gave me several indications that I followed for worse, it does not let me make calls or receive them. I've tried to reverse the process with remove non-stock law, but now it doesn't even recognize the phone. Let's see if anyone has had a similar problem and knows how to fix it, thanks.'