Traffic to Call Center?
 

Hi,

I have been doing pay per call for a little while now and I have heard from some that there are affiliates driving 1000s of call per day to some campaigns. My question is what other call based traffic is there other than yahoo/bing, google search, and call transfers? I know some mobile advertising networks offer click to call on there display ads, but those are not targeted ads so I can't imagine there being a ton of volume and if there is any calls from that the quality must be atrocious.

Thanks for your help!

MS