It should be noted that in the prior art, when the UE accesses an SAE through the EUTRAN, the default bearer exists, and the default bearer cannot be deleted, and if the default bearer is deleted, the dedicated bearer corresponding to the default bearer will be deleted as well; when the UE accesses the SAE through the GERAN/UTRAN, the default bearer also exists, after being attached to the GERAN/UTRAN, the UE having an EUTRAN ability activates an interactive or background PDP context. However, when a UE of legacy (Pre-R8, the network before the 3GPP R8 version) accesses an R8 (the 3GPP R8 version) network, the UE of Pre-R8 does not know the concept of the default bearer, thereby problems for the subsequent operations are caused. For example, after accessing the network, the UE of Pre-R8 firstly activates the dedicated bearer (a GBR bearer), thereby causing problems for the operation of the SGSN/SGW/PGW. The UE of Pre-R8 initiates deactivation of the main PDP context, and as the main PDP context (default bearer) cannot be deleted, problems for the operation of the SGSN/SGW/PGW will be generated as well.

Therefore, embodiment of the present invention provides a data communication method to solve the problems. In this embodiment, the PDP context establishment and the PDP context deactivation are respectively described.

A. PDP Context Establishment

In this embodiment, the process may be divided into the following types according to different processing modes.

A1. An SGSN performs the processing; specifically, in an eighth embodiment, as shown in FIG. 7, a PDP context establishing process initiated by a UE is described.

In step 701, the UE sends an Activate PDP Context Request message to the SGSN.