Online Food Shop - No Phone Signal

[NeedsImprovement]

So I'm with my lovely inlaws and they have no phone signal anywhere near their home. They are in their 80s.

They want to do online shopping but each time they check out, it says "we've sent a 6 digit verification code to your phone" which they cannot receive.

Does anyone why this code is needed? I remember one bank saying it was only due to that business not being registered for something - is this true? Or is it just a way to prevent fraud and we will always have this? What do people do if they have no phone signal?

This may no longer be true but I remember it used to be that a text could be sent to a landline and it would come through as a sort of robotic voice reading out the text. Maybe that would work? I don’t have a landline so can’t check!