The Nokia 6300 4G supports VoLTE (Voice over LTE) in principle, but only one SIM card can use VoLTE as it does not offer dual 4G LTE for both SIMs at the same time. This means that you can make calls via 4G with one SIM card, while the other SIM card is not VoLTE-capable at the same time. VoWiFi (WLAN telephony) is also supported, at least for one SIM card.