I need a phone number. I can have two calling cards and send messages and receive two cards at the same time.

Without this function, each SIM is an identification medium in the network. According to you, where did the call come from? It is unrealistic to connect at the same time. Theoretically, a number must be unique in the network, which is different from the extension of fixed telephone at home. Because the extension is connected to a line, you can listen at the same time, but the mobile phone can't. If you get it out like this, it will definitely conflict.

For example, now two mobile phones A and B are using the same number, so C calls and A answers, so according to the identification of the system, B is also in this identity, which means that B can also access this call, but from the perspective of C's mobile phone, its communication channel is unique, which means that there must be one that cannot be connected, so which one can be connected? The same is true of text messages. Someone sent a text message to this number and was divided into two mobile phones. Is it one text message or two text messages? The system receives feedback information, one is received and the other is not received. Does the system think it has been received or not? These are all problems that cannot be solved for the time being.

Therefore, it is feasible to use one card and two numbers for a mobile phone, and there is already such a service, but it is unrealistic for two mobile phones to use one number at the same time, at least for now.