Check the network standards supported by the mobile phone. What mobile phone standards are supported by the mainstream is what version. If they all support it, it will be full netcom. Operator network standard: mobile network standard: 4G: mobile TD-LTE；; ; Mobile 3G: TD-SCDMA; Mobile 2G:GSM Unicom network standard: 4G: Unicom TD-LTE, Unicom FDD-LTE；; ; Unicom 3G:WCDMA；; ; Unicom 2G:GSM telecommunication network standard: 4G: TD-LTE, FDD-LTE；; ; Telecom 3G:CDMA 2000；; ; Telecom 2G:CDMA