Network access authentication method and device

A device for wireless communication, comprising:

• a processor;
• and
• a memory including processor executable code, wherein the processor executable code upon execution by the processor configures the processor to:
• receive an attach request originated from a user equipment, the attach request carrying a temporary identifier;
• transmit a request message to a first serving network that previously served the user equipment to obtain a user context from the first serving network according to the temporary identifier carried in the attach request;
• receive a response message from the first serving network indicating a failure by the first serving network in retrieving the user context caused by the first serving network not being able to find the user context;
• transmit, in response to the response message indicating the failure of the first serving network, an identity request message to the user equipment, wherein the identity request message includes an identity type indicating that an encrypted subscription identity is requested;
• and
• receive, in response to transmitting the identity request message to the user equipment, an identity response from the user equipment including the encrypted subscription identity,
• wherein the processor is further configured to:
• receive a second attach request originated from a second user equipment, the second attach request carrying a second encrypted subscription identity;
• transmit an authentication request message to a home network, wherein the authentication request message includes the second encrypted subscription identity, and wherein the home network is determined based on a Mobile Country Code, MCC, and a Mobile Network Node, MNC, carried in the second encrypted subscription identity;
• and
• receive an authentication response message from the home network, the authentication response message comprising a decrypted subscription identity.

A non-transitory storage medium having code stored thereon, the code upon execution by a processor, causing the processor to implement a method that comprises:

• receiving, by a second serving network, an attach request originated from a user equipment, the attach request carrying a temporary identifier;
• transmitting, by the second serving network, a request message to a first serving network that previously served the user equipment to obtain a user context from the first serving network according to the temporary identifier carried in the attach request;
• receiving, by the second serving network, a response message from the first serving network indicating a failure by the first serving network in retrieving the user context caused by the first serving network not being able to find the user context;
• transmitting, by the second serving network in response to the response message indicating the failure of the first serving network, an identity request message to the user equipment, wherein the identity request message includes an identity type indicating that an encrypted subscription identity is requested;
• and
• receiving, by the second serving network in response to the transmitting the identity request message to the user equipment, an identity response from the user equipment including the encrypted subscription identity,
• wherein the method further comprises:
• receiving, by the second serving network, a second attach request originated from a second user equipment, the second attach request carrying a second encrypted subscription identity;
• transmitting, by the second serving network, an authentication request message to a home network, wherein the authentication request message includes the second encrypted subscription identity, and wherein the home network is determined based on a Mobile Country Code, MCC, and a Mobile Network Node, MNC, carried in the second encrypted subscription identity;
• and
• receiving, by the second serving network, an authentication response message from the home network, the authentication response message comprising a decrypted subscription identity.