Question Is the sim card the problem why AO3 Galaxy won't allow answering or making calls?

[TrishM]

My friend in another state went from a moto g7 with a probably bad sim card, to an AO3 galaxy. Before she could stop the worker in the small store, he put the g7 sim card in the AO3. This store doesn't sell sim cards. She can see when a call comes in, but she can't answer it. Doesn't matter how she slides to try and answer, it won't. She also can't make calls. She's on s.s., so very low income, and has medical and weather issues, which doesn't make it easy to go out shopping for anything. Is it the sim card that's the problem with the cell or something else?