> Postal services worldwide started refusing incoming nigerian mail in the late 1990s because investigations showed that more than 1/3 of the postage stamps on incoming mail were fakes and the amount of mail was frequently misdeclared - which meant they weren't being paid correctly for delivery.
Indeed, and that's where I'd start.
If UK telcos were required to refuse calls from "dodgy" (mostly foreign) telcos then the problem would soon reduce considerably. If a telco find that it can't terminate calls made by it's subscribers then it faces two choices - either fix it's problems or see it's customers leave very quickly. Since the latter means certain death, and probably legal action by the shareholders against the board, they will most likely clean up their act.
But what is "dodgy" ? I guess a system like the big mail providers use - if enough customer flag your mail (call) as spam then the sender gets blacklisted. Needs some oversight to avoid gaming of the system, but it would quickly weed out the bad telcos that are permitting this sort of thing.
Another clue - if the data received is shown to be bad, then the telco needs to up it's game.
Going back a while as there were valid reasons for a telco to not have the required data (old systems etc). I find it hard to believe that any of those are still valid.
Biting the hand that feeds IT
