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What is a soft bounce and a hard bounce in SMS?

The term "SMS bounce" refers to an SMS that has failed to be delivered and resulted in an error message being sent back to our servers.

We differentiate between the two types of bounces: soft bounces and hard bounces.

🟠 Soft bounces 🔴 Hard bounces

A soft bounce is a temporary delivery failure. When an SMS soft bounces, it means that, in most cases, the phone number is valid and your SMS has reached the destination terminal of the recipient, but the phone carrier rejected it. It means that your SMS has not been delivered to your recipient.

There can be many reasons why your recipients did not receive your message and the message resulted in a soft bounce:

  • The SMS was sent to a landline phone number.
  • The recipient's phone is turned off or doesn't have service at the delivery time. 
  • The phone number or country code is invalid.
  • The SMS expired within the operator.
  • The SMS sending failed or was rejected due to suspicion of SPAM on the operator network.
  • The provider failed to deliver the SMS for unknown reasons.
  • The SMS in its current form is undeliverable.
  • The SMS sending has failed due to a temporary condition on the operator network. 
  • The recipient is currently unreachable.
  • The SMS sending has failed due to a temporary phone-related error, e.g., SIM card full, SME bust, or memory exceeded.
  • The SMS was sent at an unauthorized time or date in the recipient's country. Some countries regulate sending hours and days.
    💡 Good to know
    Ensure you check the SMS marketing regulations in your recipients' countries. For France, Brevo automatically reschedules messages sent outside the allowed hours to the next permitted slot. 

How does Brevo handle soft bounces?

❗️ Important
SMS that register a high rate of soft bounces are automatically suspended by our system to protect your sender reputation.

Here's how we handle soft bounces at Brevo:

  • When an SMS campaign returns a soft bounce, we mark it as such in the campaign report. If you want to resend the campaign to the contacts who returned a soft bounce, you can requeue it by clicking More > Requeue under the SMS campaign.
  • When a transactional SMS returns a soft bounce, we mark it as such in the transactional report and logs. Note that you cannot resend a transactional SMS.
💡 Good to know
The above information is also applicable to test SMS.

Best practices to avoid SMS bounces

As you can notice, some reasons are independent of us and from you. However, some of the reasons for soft bounces could be avoided on your side such as the phone number or country code being invalid or the SMS being sent at an unauthorized time or date. Follow our Best practices for SMS deliverability to prevent your SMS from resulting in a high number of soft bounces or being suspended. 

Where can I view my SMS bounces?

When an SMS bounces, phone carriers usually provide the error message of the bounce to Brevo. This error message helps you identify the delivery error by including:

  • The time and date when the SMS bounced.
  • The reason for the bounce.
💡 Good to know
Sometimes, phone carriers don't provide the reason for the bounce to Brevo. In this case, the reason appears as "unknown". 

You can view the error message of a bounce from the details page of the contacts who bounced. To find which contacts bounced, you can segment them using our SMS "classed as a soft bounce" or SMS "classed as a hard bounce" conditions.

1️⃣ Segment the contacts who bounced

  1. Go to Contacts.
  2. Click + Add a filter.
  3. Select the following condition:
🟠 Soft bounces 🔴 Hard bounces
  1. SMS > SMS classed as "soft bounce"
  2. Choose which campaigns > SMS Name > Is exactly > enter the name of the SMS campaign that soft bounced.

2️⃣ Check why the SMS bounced

  1. From the segmentation results, click a contact to access their details.
  2. From the history, go to the Marketing tab.
  3. Under the SMS campaign event of the SMS campaign that bounced, click Show details.
  4. The error message shows next to the Soft bounce or Hard bounce event.

Do I pay for bounced SMS?

Yes, you are charged when you send the SMS, even if it bounces. For SMS campaigns, you are also charged every time you requeue it.

If my SMS bounces, do I get a refund?

If our platform encountered a technical issue that caused your SMS to soft bounce, you may be entitled to compensation. Contact our support team by creating a ticket so that we can discuss your options. For any other case, you will not be entitled to compensation.

⏩ What's next?

🤔 Have a question?

If you have a question, feel free to contact our support team by creating a ticket from your account. If you don't have an account yet, you can contact us here.

If you’re looking for help with a project using Brevo, we can match you with the right certified Brevo expert partner.

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