什么时候使用 deactivate pdp context accept

对于业务，有四种，interactive、background、streaming、conversational
一开始的时候使用了一种业务，比如，后来又要WAP，这两种业务需要不同oS，因此才会要求修改。

4 PDP Context Modification
An SGSN can, due to subscriber data changes, modify parameters that were negotiated during the PDP context activation procedure. For example, the QoS and radio priority parameters can be modified.

The following PDP context modification procedures are supported:

MS-Initiated PDP Context Modification
SGSN-Initiated PDP Context Modification
GGSN-Initiated PDP Context Modification
RNC-Initiated PDP Context Modification
When an SGSN is requested to modify a PDP context, it transparently forwards the protocol configuration option received from the MS to the GGSN, or in the other direction, from the GGSN to the MS.

To determine the PLMN in which the MS is located, the Mobile Country Code (MCC) and Mobile Network Code (MNC) where the MS is registered are forwarded to the GGSN. When using the GPRS Tunneling Protocol version 1 (GTPv1), the IMEISV and the radio access technology employed (GSM or WCDMA) are also forwarded. The forwarding of MCC, MNC, IMEISV, and radio access technology is handled through Access Aware Core Edge (AACE). The function of AACE is partly restricted when the SGSN is configured to support multiple PLMNs. In this case, the SGSN does not indicate a change of MCC and MNC at an Intra-SGSN RAU.

4.1 MS-Initiated Modification
An MS might request PDP context modification to change the negotiated QoS. WCDMA System MS might also request it to reestablish preserved RABs.

4.1.1 Traffic Case
The MS-Initiated PDP Context Modification procedure is shown in Figure 4.

Figure 4 MS-Initiated PDP Context Modification Procedure

The following steps describe the MS-Initiated PDP Context Modification procedure:

The MS sends a Modify PDP Context Request message to the SGSN.
The SGSN sends the GGSN an Update PDP Context Request message, which optionally includes the protocol configuration option.
The GGSN responds with an Update PDP Context Response message to the SGSN. For no response, see Section 4.5.
For GSM, the SGSN exchanges information related to ongoing user data transmission with the BSS, and initiates modification of the Packet Flow Context, see Section 6.
For WCDMA Systems, the SGSN and RNC exchange information for modifying the RABs between the MS and the SGSN, see Section 7.2.

For WCDMA Systems, the radio bearer between the RNC and the MS is modified, or released and reestablished, see Section 7.2.
The SGSN sends a Modify PDP Context Accept message to the MS.
4.2 SGSN-Initiated Modification
The SGSN can initiate a PDP Context Modifica