telecom industry here, honestly, nothing. SS7/PSTN are horribly broken.
only thing that will fix it is burning it to the ground.
fcc regulations and penalties mean nothing to shady offshore grey market scam call centers in india using suspicious/unethical voip providers and methods of getting phone traffic to the US/Canada.
shaken/stir is a joke
set up a voip based system with IVR on your incoming DIDs that asks the caller to input a short series of digits to be connected, then have that series of digits ring your real line.
only thing that will fix it is burning it to the ground.
fcc regulations and penalties mean nothing to shady offshore grey market scam call centers in india using suspicious/unethical voip providers and methods of getting phone traffic to the US/Canada.
shaken/stir is a joke
set up a voip based system with IVR on your incoming DIDs that asks the caller to input a short series of digits to be connected, then have that series of digits ring your real line.
it will filter out about 98% of the crap