All smrtPhone accounts require a pre-paid credit to cover usage such as buying new phone numbers, making voice calls, sending text messages, or maintaining call recording storage.
If you are manually refilling your available credit, it is possible that your balance will go into the negative. This typically happens when your usage has outpaced your ability to recharge your balance.
When your account goes into the negative, it will be paused until you can recharge your balance. Once you have re-upped your account, you can go back to using smrtPhone as usual.
One way to avoid this is to sign up for Auto Top-Up. This is where you give us permission to charge your credit card when your balance falls below a threshold you set. You also determine the amount of the Top-Up. You can read more about Auto Top-Up here>>