Question: In a telecom network, what triggers the transfer of the 'Time Zone' Information Element (IE) from the Mobility Management Entity (MME)/Serving GPRS Support Node (SGSN) to the Serving/PDN Gateway (S-GW/P-GW) or Traffic Detection Function (TDF)?
Option 1: Periodic Location Update by User Equipment (UE)
Option 2: Handover Procedure between Different Base Stations
Option 3: Mobile-Initiated PDP Context Activation
Option 4: IP-CAN Bearer Activation/Modification Procedure
Explanation: The 'Time Zone' IE is transferred during the IP-CAN bearer activation/modification procedure, involving setting up or modifying IP Connectivity Access Network (IP-CAN) bearers, necessitating the exchange of relevant parameters like the time zone for seamless network operations and accurate charging.