Question: In a GERAN to UTRAN handover during a Routing Area Update, how does a new SGSN handle DRX parameters received from both the MS (in the Routing Area Update Request) and the old SGSN (in MM Context)?
Option 1: The new SGSN uses the DRX parameters provided by the MS in the Routing Area Update Request and ignores those received from the old SGSN.
Option 2: The new SGSN combines both sets of DRX parameters to optimize paging group calculations.
Option 3: The new SGSN prioritizes the DRX parameters sent by the old SGSN in MM Context over those provided by the MS.
Option 4: The new SGSN requests additional information from the RNC/BSC before deciding which DRX parameters to use.
Explanation: This is correct because, according to the specified behavior for supporting mobility from pre-Release 99 SGSNs, if a new SGSN receives DRX parameters from the MS during a GERAN to UTRAN Routing Area Update, it should utilize those parameters and disregard the same information received from the old SGSN in the MM Context. This ensures seamless handover and correct paging group calculation based on the most current settings provided by the MS for the new network context.