This time I'm even thinking of getting a pay-as-you-go cell phone so that I don't have to give anyone my real cell phone number to start with. My real cell phone number is dearer to me than even my home number these days!
I really don't see the issue with giving out your cell phone number. If you don't want to answer it... you don't. And... people can find out where you live if they really try... they don't always need a cell phone number to do it.

I understand being safe... but heck... you can see who is calling and ignore them.