Network access method and system, terminal, access network equipment and core network equipment

The invention discloses a network access method and system, a terminal, access network equipment and core network equipment, and relates to the technical field of mobile communication. The method comprises the following steps: the terminal reports terminal type information and card type information to the access network equipment; the access network equipment initiates an access process to the corresponding core network equipment according to the terminal type information and reports the card type information of the terminal in the access process; and when the core network equipment judges that the card type information of the terminal does not match the current network type, the core network equipment does not initiate an authentication process and directly goes into a service process. With the above scheme, a card does not need to be changed, and a user can still use the old card to carry out service communication with a new network, thereby solving the problem of card changing in the network upgrading process.