Question: In Voice Group Call Service (VGCS) as per 3GPP standards, how is an acknowledgement message typically sent from a mobile station with acknowledgement facilities?
Option 1: Using an appropriate data service to a predefined address or with a predefined short code stored on the SIM/USIM card.
Option 2: Through a dedicated voice channel allocated for acknowledgements only.
Option 3: By modifying the original voice group call's audio stream to embed the acknowledgement.
Option 4: Via SMS to a network-specified acknowledgement recipient.
Explanation: This is correct because, according to the VGCS specifications, mobile stations with acknowledgement capabilities are required to send an acknowledgement message using an appropriate data service. This approach allows for efficient and standardized communication of acknowledgements without disrupting the primary voice group call service, leveraging existing data service infrastructure (e.g., predefined addresses or short codes stored on SIM/USIM cards).