Carrier Violation Overview
If too many text messages are sent to mobile numbers hosted by the same carrier (e.g., Verizon, AT&T, etc.), the recipient's carrier may begin to reject text messages from the sender's number due to a "carrier violation." Individual messages may be flagged as "carrier violations" as well, depending on the content of the text message. This is actually an intentional feature, implemented by the carriers, to prevent mobile numbers from unwanted spamming.
How do I know if my messages are being filtered?
There are other error codes, such as 30003, which have a more generic error message, but are often also associated with carrier filtering. In these cases, the carriers do not want to indicate to the sender that they are performing filtering.
Why do carriers have content and spam filters?
How do carriers filter messages?
Links (Updated 2/2/2018)
Based on new information and from observing carrier behavior, including a link in a message is now increasing the risk of that message being filtered. This applies even to single messages not sent as part of a batch. Shortened links, using services such as bit.ly and goo.gl seem to be filtered at a higher rate than messages containing standard, full links - but both may put the delivery of your message at risk. For this reason, links should be used sparingly, and potentially only as part of a followup message to a student you are already communicating with.
If a message with a link does come back with a delivery failure, it is usually possible to resend the message right away without a link, and have it delivered successfully.
How do I prevent my messages from being filtered?
- Avoid sending mass texts from the same phone number to multiple lists of students in a short time period.
- As the amount of unique students that are being texted per day by a single number increases, so does the risk of carrier filtering.
- Avoid sending links if possible - shortened links specifically, because they hide the actual destination, put a message at a much higher risk of filtering by certain carriers
- Utilize the "Send as staff member" function (Admins only). This function will send text messages from each staff member's texting number (rather than one single texting number), therefore reducing the amount of messages that are sending per phone number in Cadence.
- Avoid confusing messages. Suspicious recipients are more likely to report messages to their carrier, and when messages are reported to carriers, it becomes more likely that future messages from that number or with similar content will be filtered.
- Avoid overly long messages, messages IN ALL CAPS, short links, hyperbole, and the use of aggressive language, as these may raise the level of suspicion of your recipients.