Method and apparatus for terminal device to access a network

An information transmission apparatus, comprising:

• a memory storage comprising instructions;
• and
• one or more processors in communication with the memory and configured to execute the instructions to:
• determine whether the information transmission apparatus is in a data-connected state;
• receive, from a core network device when the information transmission apparatus is in the data-connected state, a non-access stratum (NAS) message, wherein the NAS message comprises identifier information of at least one public land mobile network (PLMN) and target network slice selection assistance information corresponding to the at least one PLMN, wherein the identifier information of the at least one PLMN and the target network slice selection assistance information comprise first identifier information of a first PLMN and first network selection assistance information corresponding to the first PLMN;
• obtain the first identifier information of the first PLMN when the information transmission apparatus accesses the first PLMN;
• determine the first network selection assistance information based on the first identifier information of the first PLMN;
• and
• send an access request message to an access network device, wherein the access request message carries the first network selection assistance information.

A computer program product comprising computer-executable instructions for storage on a non-transitory computer-readable medium, that when executed by a processor, cause an apparatus to perform a method comprising:

• determining whether the apparatus is in a data-connected state;
• receiving, from a core network device when the apparatus is in the data-connected state, a non-access stratum (NAS) message, wherein the NAS message comprises identifier information of at least one public land mobile network (PLMN) and target network slice selection assistance information corresponding to the at least one PLMN, wherein the identifier information of the at least one PLMN and the target network slice selection assistance information comprise first identifier information of a first PLMN and first network selection assistance information corresponding to the first PLMN;
• obtaining the first identifier information of the first PLMN when accessing the first PLMN;
• determining the first network selection assistance information based on the first identifier information of the first PLMN;
• and
• sending an access request message to an access network device, wherein the access request message carries the first network selection assistance information.