Why is my account balance negative? 

When Credits Total 0 or Less

It can happen: you receive a notification from CallFire that your account balance has fallen below zero (0) credits. How is that possible? To answer that, we first need to explain how CallFire sends out your calls and texts. Most users want their messages to be delivered as quickly as possible, so the CallFire system "grabs" a large selection of phone numbers, let's say 100 or so, and calls them all at the same time. As the calls are in progress, we deduct credits from your account balance, but we can never know how long each call will last. Certain calls can last much longer than others, and these will cost more. Now when that batch of 100 calls has been completed, the CallFire system attempts to grab the next 100 numbers, but it checks your balance first. If it is at 0 or in the negative, the campaign will stop. Additionally, CallFire will never disconnect a call in progress. You will always be able to finish your conversation, even if the call costs more than your available credits.

You can protect yourself and keep this from happening by setting up an auto-pay feature that will fund your account if the balance falls below a predefined threshold. You will find that setting on the main Account Settings page.