Comment Re:Or the phone companies could stop it at the sou (Score 1) 52
Until recently when we switched to VoIP I ran a few telephone switches for work. I could send arbitrary caller ID through the phone network, but didn't because we want people to be able to call our customers back if they're called.
If I had sent a fake caller ID, could the destination phone company figure out that I was sending it? Yes, but it would be non-trivial once it had gone through a few PSTN switches run by different phone companies and they all had to track it back through their switches to find out where it really came from.
It may be easier with VoIP but I don't really know how that works once the call leaves our system. With the old PSTN switches it would be something like "yeah, the call is coming in on line 12 and leaving on line 17".