Question: In a 3GPP system with multiple prepay services (e.g., internet access, m-commerce), what happens to ongoing charging for a specific service when the associated prepay account credit is exhausted or expired?
Option 1: The ongoing charging continues until the subscriber manually stops the service.
Option 2: The ongoing charging information is immediately interrupted (within a few seconds) and prevented from further depletion.
Option 3: The system automatically switches to a default postpay account if available, to continue the service.
Option 4: The subscriber is redirected to a top-up page to replenish the prepay account before the service can resume.
Explanation: This is because, as per the requirements for prepay services in a multi-service environment like 3GPP, all ongoing charging information related to a specific prepay account must be immediately interrupted (within a few seconds) as soon as the prepay credit of that account exhausts or expires. This ensures that the subscriber does not inadvertently incur additional charges once their prepay credit is depleted.