While the iPod touch runs the same operating system as the iPhone and includes nearly all its features, it can't make phone calls over a cellular network. To use your iPod like a phone, you have to choose one of several alternative methods, all of which require a Wi-Fi connection. You can use FaceTime for calling other users on Apple devices, or select one of numerous apps from the App Store that offer phone service.
FaceTime on the iPod
All models of iPod touch beginning with the fourth generation support FaceTime. This built-in app lets you make both audio and video calls over Wi-Fi for free. It has a major limitation, however, in that it only works to call other Apple devices, including iPhones dating back to the iPhone 4 and iPads starting with the iPad 2. To set up FaceTime, open the "Settings" app, press "FaceTime" and turn the service on. Log in with your Apple ID, and then use the FaceTime app to make calls.
Skype for iPod Touch
If you already use Skype on your computer, downloading the iOS app allows you to access most of the same features on the iPod touch. The app can make audio and video calls, as well as host text chats. As with the desktop version, calls between Skype users are free, but calls to regular phone lines require Skype credit or a paid subscription.
Vonage Mobile and Extensions
Vonage offers two apps that support calling on the iPod touch. Vonage Mobile provides free calling to other users of the app, but has one major limitation when used on an iPod: you can only place outgoing calls, not receive calls. Alternatively, if you subscribe to Vonage for home phone service, you can use the Vonage Extensions app. This app ties into your existing Vonage account, letting you call any phone number and billing your account of minutes accordingly.
Combined with an existing Google Voice account, you can make calls from an iPod touch using Google's Hangouts app. Google offers free calling within the U.S. and Canada. Calls to other regions require purchasing credit for your account. You can also receive incoming calls through Hangouts by opening the app's settings, tapping "Phone Number" and then "Incoming Phone Calls."