While calling is not a direct feature of the Kindle, the Kindle Fire HD and Fire HDX come equipped with a microphone and camera that allow a user to make video calls using Skype. Skype is free to install from the Amazon App Store.
After downloading the Skype app to the Kindle, tap the app to open it, sign into a Skype account and then tap the Contacts list, Recent list or Call Phones list to make a call. Skype for Kindle Fire HD offers free voice and video calls over a Wi-Fi connection to other Skype users. For a fee, Skype users can make calls to landlines and mobile phones.