Question: What is the primary condition under which an unsolicited result code `+CCWV` is sent to indicate the approaching maximum value of the Accumulated Call Meter (ACM), assuming the call meter warning event is enabled?
Option 1: When the ACM reaches its absolute maximum value, triggering a system alert.
Option 2: At the initiation of every new call, regardless of remaining call time.
Option 3: Randomly, as a precautionary measure to check system responsiveness.
Option 4: Approximately when only 30 seconds of call time remain before reaching the ACM maximum value.
Explanation: This is correct because the `+CCWV` warning is issued shortly before the ACM maximum is reached, specifically when about 30 seconds of call time are left, ensuring the user is alerted just before exceeding the limit.