Comment by kemayo

> Not professional, not an option for some calls.

Callers can't (well, shouldn't) expect to be able to reach you immediately by calling you. There's a lot of valid reasons to not answer your phone. You might be driving, you might be in the bathroom, you might be getting lunch in a noisy place, you might be in the middle of a different important conversation, etc.

At which point the caller needs to realize that the "professional" thing to do is leave a message if they want to be called back. (Or try calling again later.) Because there's enough junk calls that expecting people to call back every missed call that didn't leave a message is just unreasonable.