I don't care if someone gave it to me for free. I still wouldn't call whatever number they gave me! For that matter, I wouldn't pay them to give me a number either.
Assume you are given a 1-800 number for your own use - people can call it and reach whatever you set up (you directly, a voicemail box, a phone menu set up, a dialup connection, whatever). The number is free and your minutes are unlimited.