SMS Delivery Statuses

Each SMS received a delivery status from the operator after this has been sent. The table below shows you the different status, their meanings, and the actions you can take to solve any issues you may have. You can find more detailed information on our Developer Page. You can always check our troubleshooting guide for undelivered SMS if you are seeing a lot of 'not delivered', 'expired', and 'sent' statuses on your SMS traffic: My SMS was not delivered





The message has been delivered and we received a confirmation via the DLR (delivery report) from the receiving network.

Not delivered

We were unable to deliver the message.

Please check the Status reasons below for additional details.

The Status reason is unknown subscriber

The receiver number does not exist, remove it from your Database.

The Status reason is unavailable subscriber or received network error

If "unavailable" the receiver headset was off or out of coverage, this should resolve eventually. Same if the reason was a "receiving network failure" it is probably already being worked on by the receiving carrier. In both cases, you should be able to successfully deliver the SMS later on.

The Status reason is capacity limit reached or carrier rejected

Carrier or country often have restrictions on SMS traffic and/or require registration. Please do check the regulation of the country you are sending to. Looks like your SMS is not compliant.


The Status Reason is unavailable subscriber

We received information from the downstream carrier that the receiver was temporarily unavailable or out of coverage. We attempted to reach it via a retry pattern but the validity period expired before we could deliver your SMS. If you are not sending time-sensitive SMS (like OTP) you could consider increasing the validity period**.

The Status Reason is DLR not received or Expired

We were unable to deliver the message. The device was possibly not connected with the A2P* network within the validity time span**.


The message has been sent, but we haven't received a delivery status yet. The Status Reason is Pending DLR

This is a temporary status and will always change to either Delivered or Not delivered (within the validity time span*).

The message has been delivered to the downstream operator or carrier and acknowledged however we are pending information on its final delivery status.

Likely the receiver wasn't available and we are attempting retry, our standard validity period is 72 hours so this status can persist for up to 3 days.

You can reduce this by setting a shorter validity period *.

If you have access to the receiving handset and its connection is fine, switch off the device and restart it after 10 seconds. This will force it to re-establish the connection with the provider. Please retest it with another message.


The Status Reason is Pending DLR. The message has been sent, it's just in the queue for delivery.

Please wait for the messages to be delivered. This may vary based on the number of messages you have and network activity.

* A2P is Application2Phone, or in this case from MessageBird to your client

** Learn more about the validity period here: Setting a Validity Period for your SMS

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