It grates me the wrong way so hard when I call someone and their receptionist/gate keeper asks if that person was expecting my call. NO NO we do not schedule every brief phone call into our calendars, so at this EXACT moment in time, NO, she is not sitting by the phone waiting for me to call. That's WHY I am calling - to speak to her about something! FFS!
And there you have a problem in a nutshell.
Businesses often do not train, or value, their reception staff and frequently management egos demand a firewall, lest their "brilliance" be interrupted by some lesser person.
For those who would like to test how well their companies deal with these "intrusions", I would suggest a simple test.
Invite a good friend to lunch or even just a coffee, ask them to call your office and ask to speak to you, then listen in on the conversation.
Please remember the solution is not to fire the "guilty", but to resolve a defective management mindset.