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Message Delivery - Carrier violation

Message Delivery - Carrier violation & Message filtered

Error - 30007

Your message content was filtered, flagged as objectionable, and blocked by the receiving wireless carriers (Verizon, T-Mobile, AT&T, Sprint, etc.). This is done by a wireless carrier for violating carrier rules or regulations. Many carriers have systems in place to protect mobile subscribers from spam or unwanted messages.

Possible Causes

  • Your message was identified as spam or unwanted messaging by the carriers (Verizon, T-Mobile, AT&T, Sprint, etc.). message filtering system.

  • Your message was flagged as objectionable and blocked by a wireless carrier.

Filtering Mechanisms

Carriers in the U.S. appear to be using adaptive (machine learning) software systems to protect their users. These systems look at both message content and volume and behave very much like email filtering systems. Messages receive a cumulative score based on how many messages have come from a phone number during a certain time period, how many similar messages have transited the carrier’s network, or if the message contains content that makes it a high match for spam or A2P. Time periods are measured by the second, minute, hour, and day.

Carriers in the U.S. usually report to Pony Express HQ when a message has been filtered. If you suddenly see that a large number of your messages are resulting in a status of Undelivered with a 30007 error, the carrier’s filtering system has probably recently identified a pattern in your messages that triggered a block.

Message Delivery in the United States FAQ

Q: I think my number or message contents may have been blocked by a carrier. Can I get the block removed?

A: No. Pony Express HQ is unable to request any unblocking of phone numbers or message bodies due to filtering unless the messaging in question is true Person-to-Person (P2P) messaging and the block was in error (this is uncommon).

However, most carrier blocklists in the U.S. for numbers use a “cooling off” period, which means that the numbers will automatically be removed from the blacklist after a period of time. The time period may vary, and carriers do not share this information with Pony Express HQ. If your message bodies do not also change, carriers’ content filtering systems will continue blocking your messages.

Q: How do I Know if my Messages are Being Filtered?

A: Pony Express HQ can’t predict filtering and does not always know for certain when a message has been filtered by a carrier. Some carriers may falsely report filtered messages as delivered to prevent spammers from reverse engineering filtering systems. In other cases, carriers will tell Pony Express HQ that a particular message has been filtered.

The error code we will use when we know that carrier filtering has taken place is Error 30007: Message Delivery - Carrier Violation.

If Pony Express HQ knows that a message has been filtered, we will pass this information to you:

  • By updating the message status to Undelivered

  • Fagging error code 30007 in your Programmable SMS Logs.

Q: Why do Wireless Carriers have Filtering Systems?

A: Wireless carriers have filtering systems for two reasons:

1. Enforcing rules or regulations about what types of messaging are allowed to that country or mobile network

Depending on the country, laws or regulations may put restrictions on certain types of messages, or even forbid certain things altogether.

2. Protecting mobile subscribers from unwanted messaging such as spam, fraud, or abuse

When mobile subscribers receive messages they find objectionable, they may file complaints, seek damages, or simply stop being a customer. All of these things reduce revenue or increase costs for carriers. Thus, it is in the best interest of carriers to protect mobile subscribers from what they consider to be objectionable content.

Q: How do Wireless Carriers Filter Messages?

A: 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, Pony Express HQ is unable to say definitively how these systems work, or why a particular message was filtered.

Q: How do I Prevent my Messages from Being Filtered?

A: Pony Express HQ works hard to keep our customers informed about the rules and regulations affecting SMS. If you are preparing to send text messages, or you suspect your messages are being filtered, first read TCPA Compliance Checklist Guidance for Text Marketing blog post.

You can also greatly reduce the risk of filtering by following these best practices:

Provide a good user experience: Users are likely to report confusing or unwanted messages to their carrier. When these messages are reported to carriers, it becomes very likely that future messages from the same number (or those with similar contents) will be filtered. In some cases, the user may have forgotten that they requested the message, so be sure to identify your business or service in the message. Also, how the message is formatted and written is important. Overly long messages, overly capitalized messages, mysterious links, hyperbole, and using aggressive language can make users suspicious of a message.

Provide clear opt-out instructions: If users do not understand how to opt-out (unsubscribe) from your messages, they may feel they have no choice but to contact their carrier to request the carrier block your messages.

Please also carefully read through the following information:

This guide is for informational purposes only. We recommend contacting an attorney to seek additional advice pertaining to the TCPA (Telephone Consumer Protection Act) and SMS - text marketing best practices in general.


Along with responsible sending, you are solely responsible for obtaining any rights or licenses to any data, including image or sound files, that may be included in any outbound sending from the Pony Express HQ platform. If you are unclear or require more information on the legalities of any message or campaign, you must consult with your attorney before using the Pony Express HQ platform. 


You should be familiar with the fines that can occur from texting someone on a do not call list or opted-out. They may vary from State to State, and it is the account holder’s responsibility to follow these laws to avoid potential legal action and fines that could be imposed by Government agencies.

The Telephone Consumer Protection Act (“TCPA”), along with the sites below and various state laws, regulations and rules, place restrictions on certain types of phone calls and text messages. Pony Express HQ owners are not attorneys and are in no way attempting to interpret any rules, laws, or regulations. You are ultimately responsible for making your own informed decisions regarding your text messages, broadcasts, and campaigns.

Pony Express HQ has a zero-tolerance policy for text messaging spam and reserve the right to immediately cancel the account for any user that does so. Don’t be that person. 🙅‍

Pony Express HQ is a 100% opt-in service. Please see our Privacy Policy, Terms Of Use, Anti-Spam Policy to learn about our position on spam and the privacy of your data.

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