"VNTT Soft-Phone is an Internet Telephony based Soft Phone that enables you to receive and make calls on your smartphone. Connection is made to the dedicated central hosted Switching system from VNTT. The App enables VoIP calls over 3G/4G/5G and WiFi networks and supports different types of codecs. Note: you need to have an account from VNTT VoIP provider in order to use this software. This is a supplier specific application and not a generic VoIP service. More information can be found on the providers website.