What is carrier blocking?

Carrier-blocked messages became common among major wireless carriers in early 2018, as mobile carriers began filtering messages that do not abide by their best practices for commercial message sending. Carrier filtering standards are determined by the wireless carrier themselves, as Blackbird has no way of changing or updating how carriers filter their messages.

What does it mean when a message has been blocked by the mobile carrier?

If a message has been blocked by the subscribers mobile carrier, this means that the message will not be delivered to or received by the subscriber. 

Why do mobile carriers block messages?

Mobile carriers have filtering systems for commercial messages for two reasons:

  1. Enforcing rules or regulations about what types of messaging are allowed to that country or mobile network.
  2. Protecting mobile subscribers from unwanted messaging such as spam, fraud, or abuse

How do mobile carriers determine which messages to block?

There is no standard practice for carrier filtering across all carriers. Filtering can range from a list of prohibited terms, to advanced machine learning systems that constantly adapt based on the messages passing through them.

Message-Content Filtering

Mobile carriers have been known to heavily filter and block all commercial messages that they recognize contains cannabis-related content. While we cannot say with certainty exactly which terms mobile carriers typically look for, we have determined that there are some specific terms that are typically found in blocked messages. 

The terms identified with trending increase in carrier filtering include:

  • Preroll
  • Concentrate
  • Weed 
  • Wax 
  • Shatter
  • Cannabis
  • Vape
  • Kush
  • CBD
  • Eighth
  • Grams
  • OZ
  • Flower
  • Strain
  • $
  • Price
  • Purchase
  • Cartridge
  • 1/8 (or any flower weight quantities)

Volume-Based Filtering 

In addition to filtering message content, phone service providers will also filter messages by volume. Carriers don’t want commercial messages being sent more than 1-2 times a week. While, they seem to sometimes tolerate one message per day, we don't advise consistently doing this and instead suggest sending a message 2-3 times a week. If you attempt to send out more than one message each day, carriers will begin putting your marketing phone number(s) on time-out. This, like content filtering, will keep your text messages from sending.

  • Carriers check the volume of activity from each phone number. If too high, oftentimes they ignore it and will not deliver it to the recipient 
  • Then, carriers check message content for spam filtering. If considered spam, again they will ignore it and will not deliver it to the recipient.

How do I know if my messages have been blocked?

Each Connect campaign that has been sent will also display that campaign's deliverability metrics. Upon opening a sent campaign, you will be presented with the campaign overview, delivery statistics, and engagement metrics. This also includes the number of messages that were Carrier Blocked.  

How do I prevent my messages being blocked in the future?

It's important to adopt our Best Practices for Sending Connect Messages to ensure (to the best of your ability) that as few messages are blocked as possible. A few suggestions for sending messages include: 

  • Avoid using cannabis-related content in your messages
  • Avoid sending messages daily, and instead opt for 2-3 messages/week
  • Avoid sending repeat messages to your full subscribers list, and instead use your segmented lists
  • Prioritize MMS messages over SMS messages 

Carrier-Blocking Resources

What are Carrier Violations?

How Does Carrier Filtering Work?

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