The VoIP services they subscribe to usually help with this to some degree in identifying common patterns to cut down on some of the spam.

Beyond that, businesses implementing call queues & bot menus is what helps cut down on the rest of it.

It’s becoming more rare to actually get in contact with a human from many businesses nowadays. Businesses seem to want users to use a bot that will help the customer do whatever it is they’re doing as much as possible.

And the only way to get to said human is through a series of menus and questions, usually confirming they actually are a customer.

Long gone are the days of calling and getting a human to give your information to.

When you call something like Bank of America, they prove you are a customer because you give them your account number or they recognize that based on your caller ID and also have to still provide SSN or date of birth, so even if someone spoofs an actual customer’s number, they’re stuck in the menu and never reach a human.

The spam calls are few and far between… when measured relatively against the fucking sales cold calls.

Avoid publishing important people’s direct phone numbers and force calls through a full time secretary or group of secretaries - if sales people call on direct lines notify them this is a private line and that you’ll block their number for repeat offenses. Make a note of the caller, company, and number - if they already have a strike refuse to do business with them… watch in glee as you slowly build up a black list of all telecom providers.