Phishing and telemarketing telephone calls

The obvious way to id them is to buy whatever it is they are selling.

So that reduces the problem to being able to cancel the transaction
once id'd, and probably using fraudulent credentials.

It might take a little more strategy than what I just described, there
are other potential pitfalls.

I wouldn't suggest that route to amateurs but it's not quite rocket

Hmm. I wonder... if you get a one-time credit card number from your
bank and limit it to $1, do you get a charge declined message in your
log identifying the merchant?



Not particularly. The car warranty and credit card robocallers are still very much at it.