VoLTE

VoLTE means Voice over LTE.

In the early days of 4G/LTE, smartphones needed to switch back to 3G networks to make voice calls. Once the cellular networks were upgraded to support VoLTE and VoLTE compatible devices came out, the 3G network was no longer needed and the radio could stay in 4G mode all the time.

Older 4G phones without VoLTE support will no longer be able to make voice calls once the 3G networks they rely on are retired.