Voice over IP (VoIP) allows a voice conversation to be transmitted as internet traffic rather than as an ordinary voice call.
This means that callers can use Wi-Fi networks or their data plans to make these calls.
These two applications are called voice over Wi-Fi and voice over 4G or voice over LTE.
Operators are currently trying to move voice calls onto 4G, since it is a more efficient use of spectrum than 2G calls and the call quality offered in these calls is better, with calls connecting faster.
