Articles
- How to send an SMS
- Send a branded text message
- Tips to send a successful campaign
- How quickly are messages delivered?
- How do I buy SMS credits?
- How many numbers can I send in one campaign?
- Global SMS coverage, all languages
- International support for Alphanumeric Sender ID
- Alphanumeric Sender ID
- What are the different delivery status and their meanings?
- Generic Sender (Overwritten sender ID)
- SMS delivered with a delay
- Why are my outgoing SMS not being delivered?
Why are my outgoing SMS not being delivered?
Non-delivery means we were unable to deliver the message. There can be multiple reasons for non-delivery, examples are:
| Issue | Explanation |
| The number format is not correct | All numbers need to be added in the international format. |
| The phone was switched off | |
| 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) | 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 phone was out of network coverage | |
| 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) | Most connection issues are resolved by simply restarting the phone as this refreshes the connection to the network. |
| 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. |
Difference between A2P (Application to Person) & P2P (Person to Person)
Please note Releans 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.