Legal Question in Civil Rights Law in Michigan

Re: Recording Phone Conversations

No, not unless he's speaking to another employee in the workplace. A workplace is not a private space.

Is it a good idea to confront your boss with this information?

No, not unless you've accepted other employment.

See:

750.539d Installation, placement, or use of device for observing, recording, transmitting, photographing or eavesdropping in private place.

Sec. 539d.

(1) Except as otherwise provided in this section, a person shall not do either of the following:

(a) Install, place, or use in any private place, without the consent of the person or persons entitled to privacy in that place, any device for observing, recording, transmitting, photographing, or eavesdropping upon the sounds or events in that place.