If the employee has caller ID at his or her desk, then they don't need to pick up the phone. If they don't have caller ID, they can still do as they would with any other adult's unwanted attention. I agree with Barbie in that if it's not threatening or harassing, I would stay out of it. You can always get that person a new extension to divert the phone calls or have the switchboard send the unwanted contacts to voicemail. Do definitely set the precedent of not becoming the office mommy but also set the precedent that if there is an exposure to contact that is unsafe (
OSHA) or violates your harassment policy or discrimination law (EEOC), then take appropriate steps to protect the employee.