Can you trace an ISP number for free?

I have tried to trace an ISP number for a friend that is suffering bullying on a music forum.I have only come across sites that charge for the service.Is there any way I can do this for free? I’m trying to help someone but don’t want to be $40 out of pocket for a search that may not even be correct.Thanks in advance.

An ISP, or internet service provider, can allow customers to access the internet by giving them the use of an IP address:
an example would be: 216.109.112.135
If you go to this URL:

http://centralops.net/co/DomainDossier.aspx

you can use a form to find out more information about that number. be sure to check the boxes for "domain whois record" "network whois record" and "DNS records"
The number above is used by Yahoo.com and indicates a relationship between Yahoo! and Hotjobs.
In their case, the IP address is used for publishing a web site – computer gamers use their IP address to access other computers. Many computer games allow to to obtain the IP address of the other players – you can us the "domain dossier" service at centralops.net to easily find out the name of the ISP that is providing the IP address. In the domain records, you should be able to find a phone number and email address for an abuse contact. Continuous abuse from IP addresses of a particular ISP or hosting company can and should be escalated to ARIN,(see note in sources) but in most cases all you need to do is find the abuse contact at the offender’s ISP and file a complaint. Be sure to include the exact time of the incident(s).

Hope that does it for you!