Non-delivery means we were unable to deliver the message. Make sure the mobile phone numbers you enter are correct and valid so you don't waste balance on messages sent to non-existent phone numbers.

There can be multiple reasons for non-delivery, examples are:

• The handset was switched off
• The handset was out of coverage
• Number is in roaming
• Number format is not correct
• An error or bug in the Application to Person (A2P) SMS connection between the handset and the carrier.
• Restrictions from local carrier regarding SMS content and deliveries, see: Country Info & Restrictions.
• The end user’s network did not enable receiving SMS messages for this subscriber (e.g. due to low balance, or a DND list for SMS services)

Unfortunately, the above causes are out of our scope. We can always look into specific messages to investigate the cause of non-delivery.

Please check the following points before reaching out to us.

1. Check if the country you’re sending messages to has any specific local restrictions that require you to register your traffic.
2. Is the recipient number valid, reachable and formatted correctly. Example Add the country prefix, and take off the + and the first 0 from the number:
   1. Dutch number, country prefix(+31): 0612345678, should be entered as 31612345678
   2. UK number, country prefix (+44): 0712345678, should be entered as 44712345678

Reach out to us with the following information:

1. At least two affected recipient number (we welcome more samples too!)
2. A description of the error you’ve encountered
3. Date and timestamps (including time zone) when the messages were sent

Difference between A2P (Application to Person) & P2P (Person to Application)

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.

If a phone is left turned on for too long without restarting it, it can disconnect from the A2P network. It might still be able to receive messages via the P2P network but will not receive any messages via the A2P network. This is why 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 after that time, the phone usually also reconnects to the A2P network.