Serving GPRS Support Node (SGSN) Overview 
Cisco ASR 5000 Series Product Overview ▄  
The SGSN determines the MS/UE‘s location and sets up a NAS connection with the MS/UE. The SGSN then sends a 
Request PDP Context Activation message to the MS/UE. 
If the MS/UE accepts the invitation to setup a PDP context, the MS/UE then begins the PDP context activation process 
indicated in the preceding procedure. 
 
 
MS-Initiated Detach Procedure 
This process is initiated by the MS/UE for a range of reasons and results in the MS/UE becoming inactive as far as the 
network is concerned. 
 
 
Figure 172.  MS-Initiated Combined GPRS/IMSI Detach 
 
The following table provides details for the activity involved in each step noted in the diagram above. 
Table 90.  MS-Initiated Combined GPRS/IMSI Detach Procedure 
The UE sends a Detach Request message to the SGSN containing the Detach Type, P-TMSI, P-TMSI Signature, and 
Switch off indicator (i.e. if UE is detaching because of a power off).