[baxuz]

Number spoofing is trivial, and SIM cards can be bought retail for as little as 1€ in the EU and many countries around the world.

You can buy them in bulk on shady sites for as little as 5c per pop.

Most abuse happens on an industrial scale, and it's trivially easy and practically free to bypass this kind of "security" feature.

[sliken]

Right, but 1€ isn't free. So if you manage to spam 1M people and make less than $0.05 * 1M = $50,000 then you are losing money.

Thus no spam on signal.