Why Was My SMS Not Delivered? Understanding the Possible Reasons

image d'une personne qui n'arrive pas à recevoir de sms avec le titre raisons pour lesquelles mon message sms n'a pas été reçu pour l'article Pourquoi mon SMS n’a-t-il pas été délivré ? Comprendre les raisons possibles

Did you recently launch an SMS campaign and find that some of your messages weren’t delivered? The reasons behind an undelivered SMS are varied and often related to technical issues. As a result, SMS messages sometimes encounter difficulties during delivery. In this article, we’ll look at the most common causes of an undelivered SMS and how to avoid them.

The Main Reasons for an Undelivered SMS

Since 2014, SMS Partner has been sending campaigns in France and internationally. Here are the main reasons we’ve encountered that can prevent an SMS from being delivered:

1. Weak Coverage Area: The Primary Cause of an Undelivered SMS

If the recipient is in a dead zone with little or no signal, message delivery becomes impossible. For this reason, don’t hesitate to check the ARCEP website to find out about dead zones.

2. Phone Turned Off

A phone that is turned off will also prevent SMS delivery.

In these first two cases, delivery will be retried for 24 to 48 hours (depending on the carrier). After that, it will be considered undelivered.

3. Non-Existent Number

If the phone number doesn’t exist or is no longer in service, the SMS will not be delivered.

Special Cases Affecting SMS Deliverability

Beyond the three reasons above, there are specific cases that can cause SMS delivery issues:

1. The Case of Free Mobile

When sending marketing messages, Free Mobile applies certain specific requirements (sender name customization, character count, etc.) that are important to be aware of. To learn more about carrier-specific requirements, check out our article on Free Mobile particularities.

2. SMS Spam

Your message shows as delivered, but wasn’t received? In that case, make sure to check your spam folder, which is only available on Android. For more information, see our dedicated article: How to avoid landing in SMS spam?

3. Number Portability: A Temporary Reason for an Undelivered SMS

If the number’s owner has requested a carrier change, message delivery may experience temporary difficulties during the transition.

Message Not Delivered: What Should You Do?

If you notice that a message was not delivered, fill out our complaint form for an “undelivered message.” We will then carry out a detailed analysis to identify and resolve the issue.

Understanding the reasons behind an undelivered SMS is essential for optimizing your marketing campaigns. By identifying the problems, you can significantly improve your deliverability rates.

FAQ about

Undelivered SMS

+

1. Is the message delivered if you are blocked?

No, SMS messages are not delivered if your number has been blocked by the recipient. You can check this by looking at the delivery status and/or the message delivery receipt. The delivery status will remain as “Sent” or “Delivered.”

+

2. What is the difference between a sent message and a delivered message?

Sent message: The message has left your phone or sending platform. It is on its way to the carrier’s network but has not yet reached the recipient.
Delivered message: The message has been successfully delivered to the recipient’s phone (even if they haven’t read it yet). This means the carrier has confirmed its receipt on the device.

+

3. How can you reduce the rate of undelivered SMS messages in a marketing campaign?

Clean your database: Remove invalid or deactivated numbers.
Segmentation: Send SMS messages at times when recipients are available (e.g., 9am–6pm).
Avoid spam content: Use clear messages that comply with carrier guidelines.
Work with a reliable provider: Choose a platform with a high delivery rate.