Can I Make a Free Call Using the Wi

Operation
As long as the setting is enabled on a Droid handset, the device can connect to Wi-Fi networks. Network usage in this mode does not use data from a wireless data plan, nor does it affect the available minutes on the device's default phone line. This makes Wi-Fi calling a good alternative when a user's phone-plan minutes are low.
Limitations
Since third-party applications do not access the Droid's default phone line, calls made on Wi-Fi will not use the default phone interface, or have access to the Droid's built in contacts list or call history. Individual applications may include equivalents of these features.
Options
Several Wi-Fi-calling apps are available as free downloads from the Android App Store. These include Google Voice, Skype, Truphone and Sipdroid.