Question: In a GPRS network, when a GGSN receives a Delete PDP Context Request for a non-existent PDP context, what cause value must it include in the subsequent Delete PDP Context Response message?
Option 1: Request Accepted
Option 2: Non Existent
Option 3: Mandatory IE Missing
Option 4: Invalid Message Format
Explanation: According to GPRS Tunnelling Protocol specifications, if a GSN (including a GGSN) receives a Delete PDP Context Request for a non-existent PDP context, it must respond with a Delete PDP Context Response message containing the cause value 'Non Existent', ensuring proper error handling and communication between network elements.