Broadband changed an awful lot. At one time the only may to make a phone call was to route it via the Public Switched Telephone Network (PSTN) because that was literally the only network in town. I've lost track of the whozits over the years but some of the basic functions of the Bell network are still there, like BellCore (or whatever they call it now) that kept track of, basically, the North American Numbering Plan where our country code is 1 followed by NPA NXX xxxx. Being issued a valid telephone number from that authority is essentially the same thing as today registering your network address/website name with the internet service provider(ISP). Alienexpanse.com is a 'dialable number' in oldspeke.
Primary Rate Interface circuits have become the commonly accepted interface standard to deliver telephony service. Still is in a lot of places. When those first showed from the PSTN I could literally publish any outgoing Caller ID I wanted. After some time that changed, but it took years.
Now here's broadband. An entirely different network exists that can carry real time phone calls just like the PSTN. Time sensitive, real time traffic like voice and video have special network requirements - upon which I made a fortune explaining all that fifty million times to dubious IT people. The accepted standard in use for this type of traffic on an IP network - and we know that's what the interwebs is - is Session Initiated Protocol (SIP). Calls are resolved by Session Border Controllers - specialized routers - and the network addresses can be about anything you want within reason, not strictly numerical. Look at the endpoint names in use of a Zoom call, for example. Or, for a long time you could have an 'internet phone number' that could have a familiar 1+ten digit NANP address. The free ones let you call other internet-only addresses and were strictly internet-resolved. Great for deployed families, that sort of thing. But the ones you pay a small fee for are to allow non-internet PSTN calls, 'outside world' calls that have a paid connection to the PSTN.
Along come Predictive Dialers (PD). Those are the annoying things that call you. You design 'campaigns' on those things. For example, if they are calling within a certain area code (NPA) and exchange (NXX) they can generate outgoing Caller ID as that same NPA NXX plus random four numbers. Unlike the PSTN and good old PRI, Internet-resolved calls are the wild west and they can publish whatever the hell they like. And they do. That's why if you call that number that's bothering you back it's never the PD that called you, and why blocking that # never works. You pick it up because you think it might be local and that's the whole point.
OK. So your phone rings and it's a PD. The way the campaigns are set up usually considers a human voice to be a success, as is a simple hang up. The first means it's trying to route the call to a contact center agent, which is what the pause you hear is. From that agent's p.o.v it's an incoming call and the app they use is telling them what campaign made the call so they know how to answer the phone in heavily accented English. In either case, even a hang up, it's a success because it's just going to keep bothering you. Means someone's there. A failure is a null condition - neither of those things. So when I get a call I just pick the phone up and put the handset down saying nothing. Sometimes, because I got old phones, I just unplug the handset for a few minutes so it doesn't even hear background noise. That is occupying a resource - it's a glue trap - the PD wants a success and to keep going, not get stuck. It'll time out in a few minutes and (if you haven't unplugged the handset) you'll hear reorder....beep beep beep beep beep.
So that's what the old phone guy does with those things. It doesn't eliminate them but I get far, far less than I used to.