PDP Context Activation and Deactivation
 

In order for the MS to send and receive GPRS data the MS must perform a PDP context activation after the GPRS attach (Shown in Figure 23). The PDP context activation makes the MS known in the concerned GGSN and communication to external networks is made possible.
The PDP context activation corresponds from the end users perspective to "Logging On" to an external network.
The difference from using a dial-up connection over circuit switched is that in GPRS the end user can have several PDP contexts activated simultaneously if the terminal supports several IP addresses.