Question: What triggers a User Equipment (UE) to send preambles on the Physical Random Access Channel (PRACH) after a cell re-selection delay?
Option 1: Receipt of a paging message from the new cell.
Option 2: Completion of a voice call on the previous cell.
Option 3: Initiation of a Location Updating procedure or Routing Area Updating procedure on the new cell.
Option 4: Detection of a neighboring cell with significantly stronger signal strength.
Explanation: The UE sends preambles on the PRACH after a cell re-selection delay to perform a Location Updating procedure or Routing Area Updating procedure on the new cell, updating its location for seamless connectivity and service continuity.