Question: What is the primary requirement for Mission Critical (MC) service interconnection between two different MC systems to enable communication between their respective MC service users?
Option 1: Dedicated leased lines for each MC service user
Option 2: IP connectivity with appropriate performance (e.g., low packet latency)
Option 3: Exclusive use of a specific wireless frequency band
Option 4: Pre-established VPN tunnels for all potential users
Explanation: For MC service interconnection to work effectively between two separate MC systems, the underlying connectivity must support the low-latency and high-performance requirements of mission-critical communications. IP connectivity, with its ability to be optimized for low packet latency, is best suited to carry both signalling and application plane protocols necessary for seamless MC service provision across interconnected systems. This ensures that critical communications meet the stringent performance needs of MC service users.