Phone carriers in the United States and Canada want to provide the best SMS/MMS experience that they can for their subscribers. For this reason, they put in place filters and other tools to prevent spam or unwanted text messages from being delivered to their customers' mobile phones.

YetiText has been helping small businesses take advantage of texting in their business communications for several years and we have identified several critical components to help your messages get delivered.

SMS Carrier Filtering in the United States and Canada

This is a brief overview of text message filtering by wireless carriers in the United States and Canada that can affect the delivery of your YetiText text messages. In this guide, you will learn how and why messages are filtered, and options for improving your delivery rates.

Filtering Mechanisms

Carriers in the U.S. and Canada 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 may receive a cumulative score based on a variety of factors, including:

  1. The number of messages that have come from a phone number during a certain time period.
  2. The number of similar messages that have passed through the carrier’s messaging network.
  3. If the message contains content that makes it a high match for spam. This can include sales or promotion type language, links commonly used in other messages identified as spam, or A2P (Application To Person) messages. A2P messaging happens anytime the message being sent is the result of an application trigger. If your CRM tells YetiText to send a message, that is an A2P message. If you manually respond to a contact, that is a P2P (Person To Person) message.

The time periods over which the carriers score text messages are measured by the second, minute, hour, and day.

To assist you in achieving optimal text message deliverability, YetiText automatically queues and throttles the send rate of your messages. When you are attempting to send a high volume of messages with similar message content, YetiText will throttle the send rate. YetiText will also help you follow the TCPA rules regarding time-based restrictions (learn more).

Carriers in the U.S. and Canada usually report to YetiText when a message has been filtered. If you suddenly see that a large number of your messages are resulting in a status of undelivered accompanied by an error message, this may indicate that the carrier’s filtering system has identified a pattern in your messages that triggered a temporary or permanent block.

Carrier Filtering - Recent Developments

As of January 2020, carriers’ rules about long code (10-digit phone numbers) A2P messaging are beginning to change. A major example is Verizon’s 10-digit long code (10DLC) A2P service which was released in January 2020. This is a service that will specifically allow A2P traffic to be sent using local numbers to Verizon subscribers, with the added cost of a small delivery fee.

As of this writing, Verizon is the only carrier in the U.S. and Canada that has announced a solution for this. However, based on conversations with carriers and network providers YetiText expects that other carriers will come out with similar solutions in the future.

FAQ: Message Delivery in the United States & Canada

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

No. YetiText 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 very uncommon).

It appears the majority of carrier blacklists in the U.S. and Canada for numbers use a “cooldown” period, which means that the numbers will automatically be removed from the blacklist after a short period of time. The time period may vary, and carriers do not share this information with YetiText (from observation it is usually up to 24 hours). If the content of your text messages does not change, carriers’ content filtering systems will likely continue to block your messages.

Q: Can I get my messages whitelisted or pre-approved by carriers?

No. U.S. and Canadian phone carriers do not whitelist messages from 10 digit long code numbers.

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