Some cellular service providers filter incoming messages. There is no standard practice for carrier filtering across all carriers. Filtering can range from a simple static list of prohibited terms, to advanced machine learning systems that constantly adapt based on the messages passing through them. Regardless of the system, carriers keep their filtering systems closely guarded secrets. Due to the ambiguous nature of these filtering mechanisms, LaunchSMS is unable to say definitively how these systems work, or why a particular message was filtered.
To avoid your messages from being blocked or marked as “filtered” by your customer’s cellular service provider we recommend that you limit your messages to 160 characters or less. Messages that contain more than 160 characters cannot be guaranteed to arrive to the customer in the correct order in some cases at all because the message has to be broken up into two separate messages.
As a general rule try not to include multiple links in your message(s) as that can also get flagged as “filtered” by cellular carriers.
If you see that your messages are more than 160 characters long then consider breaking them up into 2 separate messages.
If you suspect that your LaunchSMS SMS number has been flagged for spam and your messages are not being received at all from your customers please call your LaunchSMS Client Success Manager so that number can be released and a new LaunchSMS SMS number can be provisioned.