Depending on the content you're producing, you may want to include phone guests. The easiest way to call phone guests over a computer is Skype.
Skype allows you to make person-to-person video calls, as well as make and receive calls from landlines and mobile phones (a nominal subscription fee's required).
Getting a Skype account is the first step. Next, you’ll need to buy call recording software.
Mac users may want to consider Call Recorder (ecamm). It costs a one-time fee of $29.95, and it seamlessly integrates with Skype. Its features include the ability to split caller and host tracks and convert file type.
PC users have a similar option in Pamela. The features--and price--are essentially the same.