It's long past time that phone calls should stop being synchronous and immediate. They are only this way because historic landlines were synchronous and immediate, and nobody changed it. This functionality should be culturally unacceptable in 2024.
Imagine if the concept of a land line never existed. Then, a startup came out with an app that: 1. allowed random people to cause your handheld device to stop what it was doing and immediately ring and vibrate and pop up a dialog over whatever app was active, 2. when you pushed a button, an instant two way audio channel was initiated, and 3. they could do all this without any authentication whatsoever--just needing to know a non-secret 10 digit number. This kind of app would fail every App Store guideline, and it would be laughed out of the ecosystem as unacceptable to end users. But in reality, it's "The Phone App" that comes pre-installed on your damn phone!! Insane that this kind of application is acceptable.