It doesn’t work. Only honest callers would follow this. In addition, looking up a number in there is paid which is less than ideal. The service itself is alread

It doesn’t work. Only honest callers would follow this. In addition, looking up a number in there is paid which is less than ideal. The service itself is already an inconvenience to its “target market” (aka telemarketers or robocallers) so at least you should make it as easy as possible to use it. I actually worked on a lawful telemarketing operation a few years back (don’t ask - desperate times called for desperate measures) and paying for TPS lookups was both a surprise and a huge problem. The only reason it seems like it works is because the US is a much juicier market for the scammers so most don’t bother with the UK, but I still see people occasionally getting tech support scams or similar so clearly there’s nothing actually preventing them from spamming the UK - for now it’s just that the US is a bigger fish.