Non-delivery means we were unable to deliver the message. There can be multiple reasons for non-delivery, examples are:
| Issue | Explanation |
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The number format is not correct |
All numbers need to be added in the international format. For more information see here: Numbers format. |
|
The phone was switched off |
Make sure the mobile numbers you enter are reachable and valid so you don't waste balance on messages sent to unreachable phone numbers. |
|
The network did not enable receiving SMS for this subscriber (e.g. due to low balance, or a do-not-disturb (DND) list for SMS services) |
|
|
The phone was out of network coverage |
Most connection issues are resolved by simply restarting the phone as this refreshes the connection to the network. |
|
There was an error in the Application to Person (A2P) SMS connection between the phone and the network. For further information, please see below (Difference between A2P and P2P) |
|
|
The number is in roaming (outside of the home country) |
For numbers in roaming, we cannot guarantee delivery. This depends on agreements between the home network and the roaming network which is out of our control. |
| The messages were not delivered due to local restrictions. |
Many countries and networks have restrictions regarding SMS content and senders. For detailed information per country, please see Country Info & Restrictions. |
|
If you are sending via the API: you are using a test key. |
Using a test key in your API request will test the connection, however it will not send out any SMS. Instead, you will receive a response code to let you know if your request was successful. If you want to send SMS you must use a live key. |
|
If you are sending via the API: there is an issue with your request. |
Successful API requests will receive a successful API response. If your SMS did not arrive, it is possible there was something wrong in your API request. If you received an error, check in the API Errors what went wrong. |
Difference between A2P (Application to Person) & P2P (Person to Person)
Please note MessageBird SMS are sent via the application-to-person (A2P) network, whereas regular SMS between end-user phones are sent via the person-to-person (P2P) network.
It is possible that a phone receives messages via the P2P network, but will not receive any messages via the A2P network which were sent at the same time. A restart of the device usually resolves the issue, as this will force the phone to reconnect to the A2P network.
Alternatively, the phone can also be put into Flight Mode for about 20 seconds. When you turn off Flight Mode again, the phone usually reconnects to the A2P network.
If you were not able to solve the issue based on the points mentioned above, please contact our support team with the following information:
- At least 3 affected recipient numbers (the more examples we get the easier it will be to investigate the issue).
- A description of the issue you’ve encountered.
- Date and timestamps (including time zone) when the messages were sent.