Well excuse me for trying to help. I'm glad you think my answer funny.

What's unreasonable about it? It seems perfectly reasonable to me, which is why I suggested it.

All you have to do is change the customer's email (the customer that does not read email anyway) to their phone's 'email' and then you'll have exactly what you asked for.  Seems a small, really minuscule, effort to accommodate your customers and get them to pay you.