They are simply checking work history of someone who worked with/for you at one time, because they are applying for a job and put your name & number down as a previous supervisor/mgr.
Call them back if you like the person, it takes like 3 minutes.
Had a message to call back to verify employment for a Mike S. Horne. To call 1-800-630-5921 x4674 and quote file# 531010.
Even though the person left a message and sounded professional, we are a company in Canada and the verification was for a company in the US (does not make sense). I did not call as we have never employed a person of that name.
Received a call from Verifications, Inc. as they are verifying my information for a new job and need additional information. If they are calling you and you are not in the hiring process with a large company, they are probably information on someone else. Not responding will just hamper that person's ability to get hired - go ahead and pick up.