I think one solution is to make sure it's possible for everyone to have a mobile phone. They are so important on so many levels.

In this situation in particular - needing to get an SMS without a number - google voice is a good solution for that issue. I used it for a while when my US bank required getting a code via SMS to a US number. I know it's a chicken and egg thing getting it going - but if there's a way to get a person in this situation a gmail account, a lot more stuff opens up from having that resource.