How CallHub Calculates Credit Requirements and How to Avoid “Low Credits” Errors

To keep campaigns running smoothly without interruption, CallHub continuously checks whether your account has enough credits to cover your usage. This article explains how the system calculates minimum credit requirements, why campaigns may be blocked, and practical steps you can take to prevent low-credit interruptions.

1. What Triggers a “Low Credits” Error

When you start or run a campaign (Voice, SMS, or Call Center), CallHub checks whether your account has enough credits to cover the expected usage. If your current credit balance is less than the calculated minimum required, the system may stop the campaign or prevent it from starting.

2. How Minimum Credits Are Calculated

CallHub uses a proactive credit coverage check (typically every minute) to estimate future usage and reserve credits accordingly.

A. Active Voice Campaigns

The system ensures enough credits exist to run all active calls for the next billing interval.

• Logic: Cover cost for the next minute of all concurrent calls
• Formula:
  Total concurrent calls × Cost per minute × Billing interval

This means the system reserves funds for the immediate next unit of usage. If your balance does not cover that, the campaign may be paused.

B. Active SMS Campaigns

SMS credits are reserved for the next 5 minutes of estimated messages.

• Logic: Estimate how many messages will be sent in the next 5 minutes
• Formula:
  Projected 5-minute volume × Cost per message

For example, if your campaign sends 100 messages per minute, CallHub assumes at least 500 messages are about to go out and reserves credits accordingly.

C. Phone Number & Keyword Rentals

CallHub proactively reserves credits for upcoming number or keyword rentals to prevent expiration during active campaigns.

• If a number’s renewal is within ~10 days, the system adds the full monthly rent to the minimum required credits.

This means even if you have credits for calls or messages, pending renewals can increase the threshold needed to keep campaigns running.

D. Call Center Campaigns

For each active Call Center Campaign, an extra 1 credit buffer is added to the minimum required credits to support stability.

3. Starting a New Campaign: Threshold Checks

When you launch a campaign, CallHub performs a one-time check that differs from the ongoing checks.

• Standard campaigns: At least 2 credits required to begin.
• Snowflake (P2P) campaigns: The full campaign cost upfront (Total contacts × rate) must be available before the campaign can start.

4. Variation by Account and Campaign Types

Reseller Accounts

For reseller setups:

• The system checks both the sub-account balance and the master account balance.
• Campaigns can be blocked if the master account lacks sufficient credits, even if the sub-account has them.

Rate Plan Differences

• Standard plans: Use default system rates.
• Custom plans: Use the specific rate card assigned to the user profile.

5. Tips to Avoid Low Credits Errors

Based on typical user scenarios, here are ways to prevent low credits interruptions:

A. Recharge Before Starting

• Ensure your balance is above the expected cost before launching a major campaign.
• For large contacts lists or high message volumes, estimate the total cost and top up accordingly.

B. Enable Auto-Recharge

• Enable Auto-Recharge with a safe threshold (e.g., if credits fall below $25, recharge $50).
• This helps campaigns continue seamlessly even if balances drop during execution. .

C. Review Campaign Settings

• Check settings like message length (segments), contacts count, estimated call durations, and rate per unit before launching.
• These directly affect credit reservations.

D. Plan for Multiple Campaigns

• If running more than one campaign concurrently, calculate combined credit requirements beforehand.
• Running campaigns together increases the reserved credits proportionally.

E. Track Expiring Credits

• Although not directly tied to the minimum requirement check, credit expiry can indirectly lead to “low credits” scenarios if older credits expire unexpectedly. Reviewing your credit expiry schedule can help you plan recharges effectively. 

F. Coordinate Number Renewals

• If you use rented phone numbers or keywords, track when they are due for renewal.
• Number renewals can increase the reserved credit threshold, so plan recharges before those dates.

6. What to Do If You Still See a Low Credits Error

If your campaign is stopped due to low credits:

• Pause and check your balance.
• Recharge manually or confirm that Auto-Recharge is active.
• Reach out to Support if you want assistance estimating how much credit your campaign requires.

CallHub’s credit model is designed to protect campaigns from mid-campaign interruptions by estimating near-term usage and upcoming costs. Understanding how the system calculates credit requirements and following the tips above will help ensure your campaigns start and run smoothly.

If you need help figuring out how many credits your upcoming campaign will use, or you want us to walk you through setting the auto-recharge, feel free to reach out to support@callhub.io. We’re here to help make sure your campaigns run without interruption.