experience with "Who's Calling"?

[mmargolin]

Does anyone out there have experience with Who's Calling, the toll-free number/tracking provider that offers keyword-based tracking for telephone leads? Anyone out there use them in combination with an automated bid management solution? Have your experiences been positive? I haven't been able to locate any information about the company outside of their own marketing materials and am curious how nobody's ever mentioned them in a column.

Thanks in advance for your help!