The facilities which people used to get in the earlier times were relatively less as compared to the present time. Even tracing a cell phone and land line number was very difficult in those days. It took days and sometimes weeks or months to get across the details of any number. Options like hiring detectives or lodging a police complaint were some of the option available. Private detectives used to charge huge fees for their services. Only rich people could afford it. But now the times have changed. And there are various cheap and effective options available to seize the unknown caller.

If you aren't sure about these services then I would recommend you to go for free services first. If you are successful in tracing the caller through different search engines like yahoo, Google, aims, msn, etc. then it is well and good. You will get the info about the caller if he has published his details in any of the social networking or other kind of websites. But as far as I know you won't get any desired result through free search.

If you are getting threatening calls from unknown callers then it is strongly recommended that you go for the paid search as this will help you to get comprehensive details about the culprit. Information is purchased by these directories from various cell phone providers. Huge amount is paid by these directories which they recover from their members. The information provided by these directories is very reliable and authentic. One gets to know about the detailed background of the caller.

Some people tend to avoid the blank calls and unknown calls in the inception. But it may prove harmful to one's life and it may even harm his family members as the caller may have some sinister intentions. So it is an essential that you take some serious action against this nuisance. Few dollars may give you your peace of mind back.