@cstross
I would also recommend doing it interactively.
Yes you need to confirm every change but you learn where your regex goes wrong
Sadly this doesn't help with missed occurrence

@vfrmedia @acm_redfox @vees
I don't see where this fact is preventing the approach from working?
Do you think the scanner will complain "this is a mobile number, you can't be a receptionist"?

The scammers work with a script (and on a tight schedule) on the first level any significant deviation from the script will lead to them hanging up.

It's important to remember that it's quite likely that the people who call you are victims themself in some way. They might be tricked into believing they are doing a valid job, the job might be their only income, or they are even forced to do the job