SMS Flooding Filter

SMS Flooding Filter – A Guide

What is an SMS flooding filter?

A ‘flooding filter’ is a security mechanism that is designed to prevent large numbers of text messages being sent to the same destination over a short period of time.

Flooding filters help to protect users from a large volume of ‘spam’ messages that could affect the performance of their device, as well as protecting SMS providers’ and mobile networks’ operating infrastructure from being overwhelmed.

The SMS Works employs a flooding filter to monitor SMS traffic, in order to protect both the recipients of the messages that are sent from its platform and its API customers, by working to ensure the on-going normal operation of its API services.

The SMS Works platform flooding filter

The traffic monitor will allow up to 6 identical or 20 varied messages to be sent to the same destination number in any given 1-hour period, at which point traffic will be throttled and messages will be rejected, to mitigate the impact on the recipient and the API platform.

In normal processing of legitimate SMS traffic it is rare for the flooding mechanism to be triggered. This can however be quite common during testing, either when developers are sending lots of messages to the same device whilst they’re building applications, or if code causes an unintended loop, sending multiple messages in a short period. The flooding filter therefore seeks to protect customers at this stage, by helping them to avoid the unintentional draining of SMS credits from their accounts.

Flooding filter error messages

If a message that you send to our API is rejected with an error code of 5020 (the flooding filter) you will need to back off from sending messages to that device again until such a time when those messages will fall outside of the flooding parameters again.

The flooding filter may not always prevent multiple messages from being delivered. We cannot offer refunds where this has occurred. Customers are responsible for testing their code thoroughly before going to production. We’ve put together a useful list of pre-flight checks that you will want to consider before going live.

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Phil Warner Technical Director
Co-founder and Director of The SMS Works, a low cost and powerful SMS API for developers. About Phil.