An access method, comprising: establishing, by a user equipment, a first connection between the user equipment and a first mobile communication network according to a first subscriber identification number stored in a SIM card of the user equipment; requesting, by the user equipment, via the first connection, a server to assign a second subscriber identification number to the user equipment, wherein the second subscriber identification number is a subscriber identification number corresponding to an entity SIM card in the server, and the second subscriber identification number is different from the first subscriber identification number and is a subscriber identification number of the country where the user equipment is currently located; acquiring, by the user equipment, via the first connection, the second subscriber identification number assigned by the server to the user equipment; initiating, by the user equipment, an access request to a second mobile communication network servicing the current location via the first connection according to the second subscriber identification number; acquiring, by the user equipment, an authentication request sent by the second mobile communication network via the first connection, wherein the authentication request includes authentication parameters; sending, by the user equipment, the authentication request including the authentication parameters to the server via the first connection, such that the entity SIM card in the server determines an authentication response according to the authentication parameters included in the authentication request; acquiring, by the user equipment, the authentication response sent by the server via the first connection; and sending, by the user equipment, the authentication response to the second mobile communication network via the first connection, to establish according to the second subscriber identification number a second connection between the user equipment and the second mobile communication network. establishing, by a user equipment, a first connection between the user equipment and a first mobile communication network according to a first subscriber identification number stored in a SIM card of the user equipment; requesting, by the user equipment, via the first connection, a server to assign a second subscriber identification number to the user equipment, wherein the second subscriber identification number is a subscriber identification number corresponding to an entity SIM card in the server, and the second subscriber identification number is different from the first subscriber identification number and is a subscriber identification number of the country where the user equipment is currently located; acquiring, by the user equipment, via the first connection, the second subscriber identification number assigned by the server to the user equipment; initiating, by the user equipment, an access request to a second mobile communication network servicing the current location via the first connection according to the second subscriber identification number; acquiring, by the user equipment, an authentication request sent by the second mobile communication network via the first connection, wherein the authentication request includes authentication parameters; sending, by the user equipment, the authentication request including the authentication parameters to the server via the first connection, such that the entity SIM card in the server determines an authentication response according to the authentication parameters included in the authentication request; acquiring, by the user equipment, the authentication response sent by the server via the first connection; and sending, by the user equipment, the authentication response to the second mobile communication network via the first connection, to establish according to the second subscriber identification number a second connection between the user equipment and the second mobile communication network.