Question: What is a prerequisite for an SGSN to support an intra-SGSN intersystem change between different radio access technologies?
Option 1: The SGSN must serve both radio access technology nodes involved in the change, and support both Gb and Iu-PS interfaces.
Option 2: The MS (Mobile Station) must be capable of handling multiple radio access technologies simultaneously.
Option 3: The intersystem change must occur within the same geographical location to minimize latency.
Option 4: The SGSN only needs to support either the Gb or Iu-PS interface for the intersystem change.
Explanation: For an intra-SGSN intersystem change to be supported, the SGSN must have control over both the original and target radio access technology nodes. This requires the SGSN to serve both nodes, ensuring a seamless handover without needing external SGSN coordination. Additionally, supporting both Gb (for 2G/3G) and Iu-PS (for 3G) interfaces allows the SGSN to manage the change across different generations of radio access technologies.