The doctor's office I go to has three Dr. Rums. There's Jim Rum, Bill Rum, and Jennifer Rum. When I call, I have to say I'm a patient of Dr. Jennifer's or, I want an appointment with Dr. Jennifer. Otherwise, I end up with her brother or her dad!
Not to be frivolous (oh no, never, nnnnno watches,of course not), but the problem can be expressed in a nutshell in this li/ovely telephone conversation:
"Hello, O'Callahan, O'Callahan, O'Callahan, and O'Callahan, Attorneys-at-Law, how may I help you?"
"I'd like to talk to O'Callahan, please."
"He's with a client just now."
"And O'Callahan?
"I'm sorry, she's in court this afternoon."
"Oh. How about O'Callahan, then?"
"I'm afraid that won't be possible; he's on vacation until next week."
"Then may I speak to O'Callahan, please?"
"Speaking..."
{Feel free to substitute for name and profession as desired)