LTE cellular mobile network access system and corresponding communication method

A LTE (Long-Term Evolution) cellular mobile network access system communication method for a LTE cellular mobile network access system comprising a SIM (Subscriber Identity Module) card interface device configured to hold a SIM card, a mobile terminal, and a NRS (No Roaming Server) accessing a domestic cellular mobile network, the LTE cellular mobile network access system communication method comprising:

• step 1) accessing, by the mobile terminal, the domestic cellular mobile network via the NRS, wherein the mobile terminal communicates with the SIM card via the SIM card interface device, and the SIM card assists the mobile terminal to perform an authentication process for accessing the domestic cellular mobile network;
• step 2) reading, by the mobile terminal, SIM card information to perform registration onto the NRS, and establishing, by the mobile terminal, an IP data channel between the NRS and the mobile terminal for transmitting the signaling data and the voice data;
• step 3) accepting, by the NRS, the registration, establishing, by the NRS, the standard S1 connection with the domestic cellular mobile network for the SIM card, and transmitting, by the NRS, registration signaling to the domestic cellular mobile network to register the SIM card on a core network of an operator;
• step 4) storing, by the NRS, information of the mobile terminal and the SIM card information, and simulating, by the NRS, a state and signaling of the mobile terminal to control transmission of a short message;
• step 5) performing, by the NRS, an authentication process with the domestic cellular mobile network based on the authentication information of the SIM card forwarded by the SIM card interface device, wherein on reception of an authentication request from the domestic cellular mobile network, the NRS performs the authentication process by accessing the SIM card via the mobile terminal, a result of the authentication is fed back to the NRS, and the NRS transmits the result of the authentication to the domestic cellular mobile network;
• and
• step 6) accessing, by the mobile terminal, the domestic cellular mobile network via the NRS, to communicate with a peer communication device by means of a call or a short message.