got a customer that keeps getting phone calls.

he knows the number.

but cant find any info on it

suggestions?

Do a search on Google for the specific 800 number. Or do a search for reverse lookup websites, as their are tons of them out there.

been there done that

number is not coming up

I assume it is a toll free number that's hitting him and he knows the dialed TFN.
Use the Ameritec ResPorg Id service.
800-337-4194. You should be able to find the carrier name and trouble reporting number.

Since you know the number, set up an auto dialer to call it every minute or so and play a recording to stop calling me! If it is an 800 number, the charges should add up pretty quickly.

Even better, call from a payphone. Costs the 800# owner an extra 50 cents per call.