How do I change pickup message

Can anyone point me to where I can set up the message to have people access the directory instead of defaulting to voice mail.
When our receptionist does not answer it is treated like any extension and asks the caller to leave a message at the tone. I would like it to point the caller to the directory instead.

I’m new at this so have patience!!

Use a ring group to dial the receptionist, make the failover destination of that ring group go to the directory.