I buy cold call leads. I get 2000 per month from the lead service.

I need a way to set up a filter so that I can see which ones of them I have called so far. 

I noticed that Zoho CRM  does not allow us to filter leads based on whether or not they have an outgoing call.

The best solution I can come up with is add a checkbox field for "has been called" and then set up a workflow rule that will check the "has been called" field once that lead has been called. I can then filter the leads based on that checkbox.

This is the best solution I can come up with. Does anybody have a good system for tracking cold calls?