How are all of these recruiters/employers away from the phone during work hours?

A good 40 percent of the time in my job search has been spent listening to my phone ring before getting the tone. I could be calling for a scheduled call and still get their voicemail. Time of day doesn't matter either. I'll call around 9 to 11, nothing. Not like those are normal work hours where someone is definitely by the phone. Call 1 to 4, still nothing. When do these people work? I just got an email from an insurance company looking to reach out and offer an interview for a new management role. I call up the number listed in the email and get nothing in return. They sent this email 15 minutes ago and in the 15 minutes since they've turned their phone off? It just makes no sense. Even recruiters I've been working with for a while now are basically unreachable 9 times out of ten. I get a lot of people prefer to text/email, but why offer a number with no stipulations if you only want to text on it?