?Cellular, Lenovo M10 FHD REL (2 GB, 32 GB, Volte) supports 4G VoLTE network, 3G CS(circuit switched) network and CSFB(circuit switched fallback) from 4G to 3G network scenarios call function. It doesnt support legacy low speed network GSM(2G), which may has function limitation on 4G to 2G or 3G to 2G network call function switch.