Are they interrupting your evenings and not leaving a message, ever? Maybe its just this 1 number on your telephone that is bugging you.
Whatever the type of call, or however many it is, you can trace who it is without anyone knowing or calling the number yourself.
There are numerous reverse lookup sites that can perform searches of landlines and cell phones.
Using a phone number trace site does, of course, require that you have the complete number as it appears in your cell phone history or on your caller ID, and that is all you need.
With that information you can begin your investigation without the embarrassment of calling someone you don't know or maybe a possible rival.
Its better to find these things out without the caller knowing.
This can also be done with numbers from the "calls out" list.
Most likely the number you are looking for is not in the public records, such as regular directories.
Unlisted and cellular numbers are not divulged without paying for access.
There are companies that purchase the rights to the databases of cellular service providers.
So if you need to research a cell or unlisted phone you will be charged a small fee.
This is basically because the companies offering cell phone traces have to pay for access to cell phone listings themselves, and so they naturally pass this cost on to the consumer.
They usually offer several levels of service including unlimited access on an annual basis.
This can end up the most cost effective program if there are more than a couple of numbers you need to check.
Finding the owner of a number is quick an efficient once you know where to go.
So get the information you need and end the mysteries.