Setting a Validity Period for your SMS

What is the validity period?

SMS delivery usually happens within a few seconds of sending your SMS. If, however, there is a reason the SMS cannot deliver immediately, operators queue the SMS and try to resend it over a certain period of time. This period of time is called the SMS validity period.

Each operator has a standard validity period, which on average is 2 to 3 days, however you are also able to set your own validity period (see more here). During this period the SMS will be in a pending state and you will see a 'Sent' status. If the phone did not become available within the validity period, the SMS will fail to deliver.

Why would an SMS arrive late?

There are a few reasons why an SMS might arrive late:

  • The number in question is not available to receive SMS. It could be that the phone does not have good service, or there is a block on the number from the operator

  • There is an issue with the network or a service outage. In these events your SMS will get queued and will be sent for delivery as soon as possible, but there will likely be some delay.

  • When sending SMS to the United States there will be an allocated throughput per second, depending on the type of Number you are sending with. Please see here for further information: US Number Options

Best practices

It can be useful to set a validity period on your SMS if the SMS contains sensitive information such as OTP codes. In these cases, you want the end user to enter the specific code during a specific window, otherwise the security can be compromised.

It can also be useful to set a validity period in events of marketing or notifications on the short term. If such SMS arrive after the fact, this can do your end users more harm than good.

If your SMS do not have any time constraint as described above, we would always advise not setting the validity period.

How can I set a Validity Period on my SMS?


If you are working from our dashboard, we currently only offer the option to set a validity period when using the Beta version of our Campaign Builder.

In the last step of the campaign planning you can set some optional Advanced settings. Here you are able to enter a validity period in minutes. Just press save once you have entered your preferred validity period and this will be set!


When sending via the API you will add the preferred validity period as an attribute in your API call. For more information on using Validity via the API please check here under 'Optional parameters': Sending Outbound SMS Documentation

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