CallRail integration with Marketo

We are looking for a way to associate Callrail tracked data back into Marketo and attribute it to Leads and those Leads to specific PPC campagins or the like through some sort of automatic integration.

If you are doing this but not using Callrail, which tool are you using and how is the integration with Marketo handled?

Any information that could be provided would be extremely helpful.  We are trying to close some reporting gaps and make this data more actionable. 

Thanks!

Chris