Using Alternative Phone Numbers For Direct Mail Marketing

[Chris Nowlin]

I have heard several people on the podcasts talking about the different phone number services they have used to filter their call leads from their different marketing campaigns. While I don't have multiple campaigns going...yet...I am working with a wholeseller who I will have managing my leads from the campaign I am running. I would like a dedicated phone number that will let him know where the lead came from, as well as, allow me to track the volume of action from the marketing itself. 

What are the different sites I can use to set up a direct phone number for him to answer? Do any of them have back-end programs to track the calls that come in? What are the pros and cons you guys have experienced when using this technology?

Thanks for the help.

Chris