Question: What information element should a mobile station supporting multicall include in the CALL CONFIRMED message if it is located in a network not supporting multicall?
Option 1: Stream Identifier (SI) with value "no bearer"
Option 2: Stream Identifier (SI) with a new value not used by any existing bearers
Option 3: Bearer Capability information element
Option 4: Stream Identifier (SI) with value 1
Explanation: According to the specification, if the mobile station supporting multicall is located in a network not supporting multicall, it shall include the SI with value 1 in the CALL CONFIRMED message. This ensures that the mobile station can correctly indicate its capabilities and requirements for the call setup process.