If it was a job offer, it was *probably*not* from a "personal" phone, but from the company offices. Thus the 'personal name' first name is not likely to be much help.
Depending on where you are, and the locale the call came from, your public library *may* have a print-copy "City Directory", or "Criss- Cross Directory" for the origin locale.
OR, if that call is _that_ important, you can go _buy_ a printed reverse directory from Polk , Hill-Donnelly , or Haines & Company
I'm not going to comment on the 'believability' of a call coming in with a real "job *offer*", where you had absolutely _no_idea_ who was calling -- didn't recognize the voice, the person's name, *or* the locale of the call.
Note for future reference: the 'lost value' of not being able to return this call would have paid for Caller-ID for _how_many_ months?
If you 'routinely' get unsolicited job offers by phone, adding Caller ID to your service would seem to be 'cheap insurance'. :)
[TELECOM Digest Editor's Note: Assuming of course, the caller did not have a block on his caller ID, or like happens to be the case quite often with company switchboards, DID numbers and similar, the caller ID was accurate and could be used. PAT]