Mobile phones can be roughly divided into four categories: single-card single-mode, single-card dual-mode, dual-card single-mode, dual-card dual-mode.
Dual-mode means that the phone supports two network modes, namely GSM network and CDMA network. Single-card dual-mode mobile phones can only use one SIM card, if the GSM network must be turned off the CDMA network, on the contrary, if the CDMA network must be turned off the GSM network, can not use two networks at the same time. The emergence of dual-SIM dual-mode mobile phones solves this contradiction, and a mobile phone can simultaneously use two networks for communication and data transmission.
Under normal circumstances, dual-SIM dual-mode mobile phones can achieve dual-standby function, but if a mobile phone is a dual-SIM dual-standby mobile phone, it generally means that this mobile phone is a dual-SIM single-mode mobile phone, that is, this mobile phone can use two SIM cards at the same time, but the network used by the two SIM cards must be GSM network.