Simultaneous Voice and LTE (Long Term Evolution)
A protocol and technical standard that allows a phone to use both voice and data networks at the same time. Specifically, when the voice network is CDMA 1xRTT and the data network is LTE (4G.)
Not all CDMA/LTE phones support SVLTE.
SVLTE only works with 4G (LTE) networks. A different but related standard - SVDO - applies to CDMA 3G (EV-DO) data networks.
SVLTE is important because CDMA 3G and LTE 4G networks were initially only built to handle data, not voice. Without SVLTE, the LTE data network is unavailable during a voice call.
SVLTE will be less important when VoLTE (voice over LTE) launches on a large scale. This will allow both voice and data to operate seamlessly on one LTE network.