Just a few minutes ago I was talking with one, he said he was from someplace someplace, not gonna try remembering, and awas going on and finaly he asked if he can ask me a few questions, I said :"Ok, but only under one condition: tell me where did you get my phone number from and I'll answer any question you will ask"
he hung up 
Bastards, I have to call my operator and ask if my number really ise hidden or what, I don't remember giving away my numbers 
Well, they might get your number from population register, if you have ordered some magazines, they might get it from any company that has anything to do with you and has your phone number
Though, that do they get your numbers depends on what they are asking
Because, example, you order one magazine, then the puplisher wants to know opinions from readers of their publishers, they ask certain type of company to do the poll, so, they give their customer register for that company in puspose of gathering the data. + The numbers WONT dissappear from their database, but well, if it is company Like taloustutkimus oy, they won't use it for selling stuff and they won't give it forward, but they might call you again, because at least Ronin may thor the phone number at random from the database
AND they can get your number from the operator in certain cases
and police has your number as well. Here is many options, and the amount may increase or may not because of your own work.
I forgot to mention the phone book
+ salesmen will dig up your number if it is possible. + and numberservices have access on any number (in the country, atleast), just that you must know the adress of the person if the number is encrypted. So not hard to get hands on a phone number eh? + lets not remember that some numbers are protected and the number services just aren't allowed to give away those numbers.
