Suitable smartphone with latest update on the software installed and supporting VoLTE functionality. For example Huawei P10/ P10 Plus/ P10 Lite/ Mate 10 Pro/ Mate 10 Lite/ P20/ P20 Pro/ Y5/ Honor 8 Lite and Samsung A6/A6 Plus/ S7/S7 Edge/S8/S8 Plus/S9/S9 Plus/J6/A8/Note 9, Alcatel .1 and 5, as well as iPhone 7 and 7 Plus, iPhone 8 and 8 Plus, iPhone X, XR, XS and XS Max, iPhone 11, 11 Pro and 11 Pro Max (with OS iOS 13)
You should activate 4G network on your smartphone, as well as VoLTE functionality. Usually it is by following the steps: Settings > About the phone > Connections > Mobile networks. The steps migt differ with the model or the brand of the smartphone. Also there is button VoLTE usually included in the Mobile networks menu.
VoLTE works whether you turn the mobile data and Wi-Fi on or off on your phone. What is required is that you have activated your phone's options for 4G network and VoLTE calls and that you are in the area of coverage of Yettel 4G network.
Activate your phone options for 4G network and VoLTE calls. This is usually done in Settings > About the phone> Connections> Mobile networks. The order and menu names may differ depending on the model of the smartphone. In the mobile network menu, there is usually a radio button to activate and deactivate VoLTE calls. When activated, the VoLTE icon will be displayed on the home screen.
If you want to disable VoLTE on your mobile phone, enter Settings and then turn off the function via the corresponding radio button from Connections / Mobile networks.
VoLTE in Bulgaria is only supported by certain models of phones - usually more modern smartphones. Maybe your phone doesn't support VoLTE, so you can't turn it on. Find relevant model with VoLTE on our website.
Alternatively, your phone may have software for another geographic region, meaning it is intended for markets outside Europe.