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Information / Solution
VoWiFi (Voice over Wi-Fi) is a telephony service provided by your network operator. It means that your network operator provides a voice call service using Wi-Fi.
Note! To use VoWiFi or Wi-Fi Calling, your device needs operator-customised software and your subscription (incl. SIM card) must support Wi-Fi Calling for the device model you're using. To inquire if your subscription and SIM card support VoWiFi/Wi-Fi Calling, contact your mobile network operator.
To make a VoWiFi call you need the recipient’s phone number.
Note! Your network operator decides if VoWiFi/Wi-Fi Calling is enabled or not in your device. (Network operators in the United States do not support Wi-Fi Calling on Xperia devices after the model Xperia XZ1 in 2017).
VoIP (Voice call over IP) is a SIP (Session Initiation Protocol) call technology using IP packet data service, for example, Skype. To make a VoIP call, a SIM card is not required but you need an IP connection using Wi-Fi or mobile data to access internet. VoIP calls are not operator dependent.