> How do you plan to prevent abuse and fraud? This seems like it could attract a great amount of misuse.

Exactly. In addition, in some countries (e.g. Germany) your client is required to have a physical address [1] not only in the country, but also in the area where they get their number.

[1] "Address" being a place where they can receive snail mail AFAIK

We comply with these regulations. To get a German landline number via our service, you must provide proof of an address in the same locality, as well as proof of ID. We supply this to the regulator, and once they approve it, we provide the number.

Many countries do not have these requirements, and for these countries you can just "click and buy".

Out of curiosity how do you verify these things?

We only verify them for completeness; then we submit them to the relevant regulator and wait for them to give the documents the OK. We don't assign the phone number until we get the OK from the regulator.

In the UK, a SIM card can be purchased without registration. We simply allow you to do that online and give you remote access to your phone (modem). One SIM card and one modem is used by one customer. It isn't really any different to walking into a shop and buying a phone and a SIM card.