I think two we can not abuse a AS9145. I think over 1000 normal clients have a big problem. For spamers like Fürst. It give only one way. The big ISP like Sunrise must make a better authorisation. This is for spammers and hobby hackers not the best way if you dial a Phonne Number 0840555555 and you take as username sunrise Password freesurf. Some of the bigger Provider has Dial in Numbers with bad or zero access control.
Blacklist all Dial in Numbers is a Problem like Sorbs...
I don't like Fürst... I think we shall canceld his phone line. This is the best way.