The sample rate for digital transmission is 8K, giving a speech bandwidth of 4K max. So the dog whistle annoys your dog, maybe your neighbors if you are lucky. Just another urban myth started by someone with an eye for a story but zilch knowledge about technical details. Similarly with the loud whistle. The transmission medium limits the volume.
If an auto scam call gets ring tone, it knows that its a live number, so not answering doesn't help much.
There are a few ways, depending on the type of call.
Anybody claiming to be from a computer security outfit, just say "hang on a moment" and gently put the phone down. Go about your business for a couple of minutes. They will go away and your line will be free again and my pension fund should benefit.
If its an automated "lifestyle survey", do the same. Just another bunch of POS cowboys like the PPI pests. This type often has an automated ringer that calls, waits for ring tone to vanish, and listens for a voice before switching through to "Rodney" with a strange accent.
If its a failed auto call, one that just stays silent, go to the investigate/report sequence.
After clearing, call 1471. On most systems this gives the caller number. Note it, google it. There will likely be others similarly annoyed. Report it via
[size=78%]http://ico.org.uk/complaints/marketing/22[/size] If the number was withheld, or it was a false number (not enough digits etc) call 1477. On many providers, this reports the last call as a malicious call. For the call to succeed, the system has to know where both ends are, so the false or spoofed numbers do not fool the system, and tech staff, if told to, can find them. This is how prosecutions are started, not off individual complaints, but off the back of a big pile. The slimeballs rely on the public not bothering to complain or being too idle to do anything.