I've said it before and I'll say it again. I never put my phone number on CL. I state in my ad if you are interested to include your phone number in your response. I rarely contact anyone who doesn't include their phone number. And the few times I did go around that rule, I've usually regretted it. I call this tactic my "Nut Case Filter". It's very effective. The ususal looney tunes don't want to provide something as personal as a phone number. The serious buyers have no problem providing it.
It' reached the point where RobbieTunes recognizes my adds as soon as they're up. So have a few of my regular buyers.