If you want to get the most out of your expensive iPad investment, you should set up free VoIP calling. You can use your iPad to make local and international calls for free, just like using a regular cell phone.
How to Make and Receive Calls for FREE on your iPad / iPad 2 / iPod Touch HD
Whether your iPad is Wi-Fi-only or you’re using it with a data plan, free calling is just around the corner when you sign up for a VoIP service. These are apps that can transmit your voice over the Internet.
To make and receive phone calls on a computer, you typically need an Internet connection, a VoIP application, a voice input device (microphone), and an output device (earphones or speakers).
The iPad offers all of that except for the VoIP service. However, getting a VoIP app or service is not a problem in terms of availability. It is easy to find a compatible service.