Firstly, the UE sends an Activate PDP Context Request message containing parameters such as a Network Layer Service Access Point Identifier (NSAPI) and a Transaction Identifier (TI) to a Serving General Packet Radio Service Support Node (SGSN). The NSAPI is an identifier assigned by the UE to identify an established PDP context, and is used between the SGSN and a Gateway General Packet Radio Service Support Node (GGSN). The TI is a transaction identifier assigned by the UE to identify the established PDP context and is used between the UE and the SGSN. After the PDP context is established, the TI is recorded by the UE and the SGSN; during subsequent operations (for example, modification and deactivation) on the PDP context, for example, in a Modify PDP Context or Deactivate PDP Context Request message, the PDP context is associated with the TI instead of the NSAPI.

In a Long Term Evolved (LTE) network system, an Evolved Packet System (EPS) Bearer ID is corresponding to the NSAPI, but the identifier is assigned by a Mobility Management Entity (MME) instead of the UE, and in an NAS message between the UE and the MME, the bearer is identified by the EPS Bearer ID, and identifier information similar to the TI does not exist.