I have numerous calls from this number.  It rings once and hangs up - multiple times a day.  When I call the number back it just rings and then disconnects.

This is some sort of collection agency.

received a number from this company asking me if i knew the girlfriend of my ex-husband on 12 years....how on earth would they have my phone number?

This is a Debt Collector named United Recovery Systems, If they call you about someone else tell them that you do not have any information. I am sure that they have the person's info from the company they are collecting for. When they called me, it was stated that they were collecting for Capital One.
The Number they gave to contact them back was 1-888-593-8401

the Number traces to North Idaho, Learn It do not answer it if you do not want to speak to a debt collector. States they are with United Recovery Systems. I believe this is a private Land Line and they do work for this company. Just My Opinion.