Question: In a GPRS network, when a Mobile Station (MS) is in the STANDBY state and needs to transmit data, what must occur first regarding its PDP context?
Option 1: The MS must perform a location update with the SGSN.
Option 2: A PDP context shall be activated before data can be transmitted.
Option 3: The MS must change its MM state to READY without any action on the PDP context.
Option 4: The SGSN will automatically activate a PDP context for the MS upon receiving a data transmission request.
Explanation: In the STANDBY state, while an MS can initiate activation or deactivation of PDP contexts, data reception and transmission are not possible until the MM state changes to READY. Specifically, for transmitting data, the MS must first activate a PDP context, as this is a prerequisite for any data transmission or reception in GPRS networks, ensuring resources are allocated and the network is prepared for the data transfer.