I don't get CL users. Post an item for sale, they send you a message with their phone number and "call me".
If I wanted to talk to a bunch of people on the phone I'd put my # in the ad folks.
I've had the same problem. I now include this line:
"I deal with Craigslist exclusively via email so please do not ask me to call you. I am in front of my email all day and will respond promptly. Thanks for looking!"