Question: What is the primary purpose of the GTP' protocol in the context of GPRS charging management, and on which interface does it operate?
Option 1: To tunnel packet data in the GPRS backbone network, operating on the Gn interface.
Option 2: To collect and transfer GPRS CDRs from Network Elements to the Charging Gateway Functionality (CGF), operating on the Ga interface.
Option 3: To manage mobility between SGSN and GGSN nodes, operating on the Gp interface.
Option 4: To secure billing data transmission between the CGF and external Billing Systems, operating on the Gi interface.
Explanation: The correct answer is Option 2 because the GTP' protocol is specifically designed for the collection and transfer of GPRS Charging Data Records (CDRs) from the Network Elements that generate these records to the Charging Gateway Functionality (CGF), and it operates on the Ga interface. This aligns with the protocol's enhanced functionality derived from the standard GTP protocol, which is primarily used for packet data tunneling in the GPRS backbone network (as incorrectly stated in Option 1). Options 3 and 4 are incorrect as they describe functionalities not associated with the primary purpose of GTP' as outlined in the context of charging management.