Carrier violations: What to avoid during SMS text marketing

14 minute read
Carrier violations: What to avoid during SMS text marketing

Text messaging, also known as SMS marketing, is a powerful tool that enables you to contact people directly. But carrier violations may be preventing your texts from being delivered.

According to Smart Insights, 97 percent of text messages are read within 15 minutes of delivery, and 45 percent of text message marketing campaigns “generate a successful ROI (return on investment).”

In fact, 54 percent of consumers have said they would like to receive promotions via text messages.

However, your SMS marketing success can suffer from simple mistakes that will get your message blocked by phone carriers.

Carrier violations - what happens when you send a message

Why would a text message not be delivered?

A text message may not be delivering to a person because they have opted out, the mobile number is invalid, or because the carrier blocked your message.

Reasons a text message won’t deliver

They are many reasons why a text message won’t deliver:

  • Carrier has blocked your message (carrier violation)
  • Mobile number is undeliverable
  • Mobile number is not MMS capable
  • Mobile number is outside your approved sending geography
  • Message contains SPAM
  • The recipient has previously blocked your message

A carrier violation occurs when the carrier blocks your message.

A carrier violation occurs when the carriers believe your message was spam, illegal, or the recipient has previously blocked your messages.

Indications you may be carrier blocked

You may see messages like this in your logs:

  • “your message content was flagged as going against carrier guidelines”
  • “phone carrier has blocked this message”
  • “your user or phone number has been blocked from sending messages”

There are other reasons why a message is not delivered, but in this article we’re going to focus on carrier violations.

Watch an on-demand webinar about SMS Marketing Best Practices

This webinar is a great overview of SMS marketing and how carriers view your text message.
Webinar SMS marketing best practices

What is a carrier violation?

A carrier violation occurs when carriers (such as Verizon, AT&T and such) receive an outbound SMS and opt to not deliver the message to the destination phone number.

The carrier prevents your message from being delivered

In other words, carriers monitor and filter SMS traffic, and if your message triggers a perceived violation from the carrier’s perspective, your text will not be delivered.

Carrier’s used advanced monitoring

The monitoring is through adaptive (machine learning) software systems that take into account the rate of sending and the content of the messages.

Similar to email SPAM filtering

Think of the spam filtering you’ve seen in email accounts, except that instead of being delivered to a spam folder, the message is not delivered at all.

According to Betwext, messages receive a “cumulative score based on how many messages have come from a phone number during a 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. Time periods are measured by the second, minute, hour and day.”

A carrier violation impacts future delivery

When your text messages are flagged, it becomes very likely that future messages from the same number (or those with similar content) will be filtered out as well.

When you receive a carrier violation, it’s best to stop all sending immediately.

DailyStory sends millions of SMS and MMS messages for our customers. And while carriers do not share their exact and unique triggers for a violation (so that spammers can’t game the system), we’ve put together some tips to avoid carrier violations during your text message marketing.

Warm up your SMS sending number reputation

Similar to how an email IP address should be warmed up, you also should take the steps to warm-up an SMS sending number. This helps establish your reputation with the carriers and allows your recipients to understand what number you send from and the type of content you send.

Warm-up your sending numbers slowly.

Remember – new numbers are unknown to recipients

Sending from a new number that recipients don’t recognize can cause opt-outs. And too many opt-outs will cause your message to get flagged as a carrier violation.

When carriers see your text messages for the first time, it’s best to keep your messages simple and concise. Most importantly, don’t use links or any sales language.

Keep the first message you send from a new number simple and request a reply.

Consider your sending number

First, it’s important to understand that in SMS text messaging, there are short codes and long codes.

Short codes

A short code is a 5- to 6-digit number used to send SMS or MMS messages. For example, a spa health club can ask customers to text RELAX to 35353 to join its loyalty program.

Toll-free numbers

A toll-free number, in the United States, is a special 10-digit number that usually starts with an 8 (800, 888, 877, 866, etc.). Originally created to allow consumers to make phone calls from land lines without out-of-area code fees.

10 Digit Long Codes (10DLC)

A long code is a standard, 10-digit number that also can be used to send SMS or MMS messages. Unlike a toll-free number, the long code is associated with a specific regional area code.

10DLC Registration

10 DLC now supports a registration process for higher volume sending.

It is possible to send 10DLC registered traffic and 10DLC unregistered traffic.

Key differences between short codes and long codes

One of the differences between the two is that short codes allow you to send thousands of messages at once, making them ideal for mass texting, while long codes can only send a limited number of messages per-second.

Short codes are expensive, but allow for higher volume sending. Long codes are inexpensive, but don’t support high volume sending.

Sending from multiple long codes

Known as snowshoeing, a common practice is to register multiple long codes to share the load because short codes can be more costly and frankly more impersonal.

Snowshoeing, registering multiple 10 digit long codes, isn’t illegal, but is not recommended.

Find out more about the pros and cons of using either short or long codes.

Pay attention to sending volume

Be aware of your texting volume and frequency.

Sending too many identical messages from a single number during a certain time period could cause that number to be blacklisted.

Use spintax, personalization and message distribution to avoid large bulk sends.

Target less than 60 messages/minute for long codes

The CTIA, which represents the U.S. wireless communications industry, advises that each long code phone number should stay under 15 to 60 messages per minute and under 200 unique recipients a day. (See more best practices from the CTIA.)

10DLC / Long codes should target less than 60 messages per-minute.

Using multiple numbers and/or building in a “cool down” period where sending is paused for a day or two can both help prevent carrier violations.

Including URLs can decrease delivery rates

Unfortunately including URLs can negatively impact delivery and increase the likelihood of getting flagged as a carrier violation.

Avoid public URL shorteners

Public URL shorteners, such as “”, “”, and others can trigger some filters.

This is because carriers do not know what content the recipient may be redirected to.

Use private URL shorteners

DailyStory includes its own URL shortener for SMS messages that include links. And, customers can bring their own custom domains too.

Use your own domain for URL shortening. Avoid public URL shorteners like

Content at the URL impacts delivery

The content on the page the URL redirects to does impact message delivery. For example, if carriers find SHAFT (Sex, Hate, Alcohol, Firearms, Tobacco) related content at the URL – even though the message is clean – the message may get blocked.

Avoid SHAFT content in your SMS and web pages.

Include gates to prevent SHAFT related URLs

DailyStory includes tools to scan the content of your URL to determine if it contains SHAFT content. If found, when the link is clicked form the SMS message a separate one time password (OTP) is sent to the recipient.

Encourage replies to your text messages

Replies, other than those used to opt-out, are a positive signal for your sending reputation.

A good practice is to send messages asking for replies to specific questions.

Use replies in your sending number warm-up campaign

We recommend that the first message sent from a new number is one that encourages a reply.

If you can craft a message that requests a response, such as “Reply YES for more info,” these help the carriers identify that your content is expected and welcomed by the recipient.

Don’t use flag words and avoid carrier violations

Aggressive language, hyperbole (exaggeration), too many CAPITALIZED words and even certain keywords can violate a carrier’s rules.

Examples of flag words

For example, the word “gift” with a $ symbol looks like spam to the content-checking programs carriers use. Repetitive content can appear spammy as well.

Terms such as CBD, 10% off, free offer or messages in all caps will get flagged as a carrier violation.

Also, consider what sort of content your customers or leads are expecting from you. Did they sign up for more promotions or other types of updates?

What about sales-focused messages?

Once your sending number is “warmed up” and your recipients are not opting out, you can add sales and promotional content.

Send what would you like to receive

A good rule of thumb? Put yourself in your recipient’s shoes and write in a way that would be compelling for you. It’s about delivering a good user experience always.

Use the DailyStory deliverability score

SMS marketing created in DailyStory is automatically scored to help you understand the likelihood that your message will be flagged as a carrier violation.

Use deliverability score to avoid carrier violations

Consider the length of your text

The structure of your text message matters just as much as the content itself.

Most critically, you should keep your text at no more than 160 characters.

SMS messages longer than 160 characters cost more

When a message is longer than 160 characters, you risk the carrier breaking it up into multiple texts. The carrier can then send those in an incorrect order and charge you for multiple messages.

Consider using MMS

A multimedia text messages, known as a picture message or MMS message, is contains attachments.

Using MMS to convey brand information.

Using an image you can convey brand information, additional text, product photos as more.

Be mindful of the content in your MMS

In the past, brands used photos to convey text that would have caused a carrier violation.

Carriers can filter MMS content using optical character recognition.

While there are still some cases where this works, some carriers do support optical character recognition and scan the contents of your photos too.

Identify yourself

Identifying yourself is both a best practice and an expectation of the FTC. And, an easy way to accomplish this is to use media in your text messages.

Include a branded image

Sending an MMS (multimedia) text message with a branded image along with your text content is a great way to help recipients know who the sender is.

And, message recipients are less likely to opt-out of messages if they recognize the sender.

Use branded URLs

While platforms such as DailyStory support built-in URL shorteners, it’s recommended that you bring your own URL.

Bring your own branded URL.

Bringing your own URL for URL shortening gives your customers reinforcement that the URL they are clicking is associated with the brand the message comes from.

If you don’t identify yourself, your text risks looking that much more mysterious and spammy to recipients.

Confirm the source of your leads

This might sound obvious, but make sure that the phone numbers you have are opted in.

Never buy SMS leads

A common but frowned upon practice in email is to purchase lists. Purchasing a list of SMS numbers is a sure-way to get your messages blocked as a carrier violation.

Maintain an audit log

All of your opted-in and opted-out numbers should be maintained in an audit log.

This should track:

  • When they opted-in or opted-out
  • How they opted-in or opted-out

Keep an audit log of all opt-in and opt-out activity.

Not only does this help you adhere to FTC guidelines, but consumers can easily report texts as spam. If they don’t really know who you even are, the likelihood of being reported as spam is that much higher.

Be upfront about opting out

A best practice is to include the text “Reply STOP to opt out” in all your marketing messages.

Honor opt-out requests

Whenever you receive an opt-out request: STOP, QUIT, UNSUBSCRIBE or more colorful responses to your messages, ensure the recipient is opted out.

If you continue to send text messages to an opted out number this will cause carrier violations and may cause subsequent messages to get blocked.

What about transactional messages?

Transactional text messages can ignore the opt-out preference of the subscriber.

A transactional message is a message that the contact has initiated, such as a one-time password for two-factor authentication.

Use a different sending number for transactional text messages.

Our recommendation is to use different numbers for transactional messages and marketing messages. For 10 digit long code numbers once a recipient replies STOP subsequent messages can be automatically blocked at the carrier level too.

What is my number is blacklisted?

Unfortunately, if your think your sending number has been blacklisted, there’s not much you can do to appeal that designation. However, many carriers will automatically remove numbers from their blacklists after a certain period of time. This amount of time has not been made public by any carrier.

To find out more about the laws regarding text messaging (that all businesses should be up to date on), check with the FCC directly.

Remain compliant with applicable laws

If you are planning to send a high volume of SMS marketing, it is important to familiarize yourself with the laws and guidelines surrounding SMS marketing. Don’t risk carrier violations.

We’ve put together some guidance for tips to keep your business out of trouble.

What to do once you received a carrier violation

If you have received a carrier violation for a message you’ve sent the available options are limited.

Below are some recommended next steps.

Stop sending the recipient text messages

Repeatedly sending SMS marketing to a number that is causing messages to get flagged as a carrier violation will cause more harm than good.

Remove the recipient’s number from your list.

Continuing to send to a number that flags your content as a carrier violation only reinforces that your sending number is misbehaving.

Report to your SMS marketing service

If you believe that the message you’ve sent should have been delivered, report it to your carrier partner.

SMS marketing platforms such as DailyStory have relationships with carriers and can help trace down why a message was blocked as a carrier violation.

However, if you are sending content that is illegal or SPAM, you may cause your account to get flagged.

Purchase a short code

Short codes were created for high volume sending and are less likely to have carrier violations when used.

Short codes have a business registration process and cost $500 – $1,000 per-month to rent.

Unfortunately not all brands will be approved for short codes and the cost for a short code can be expensive.

Register for 10DLC

If purchasing a short code is not an option, consider registering your brand and campaign with 10DLC.

10DLC has a similar registration process to short codes and not all brands will be approved.

Once registered, your 10DLC sending number is given a higher throughput sending limit and is subject to less filtering.

Recycle your sending number

We recommend using this as a last resort, but your sending number can be recycled and replaced with a new sending number.

Cycling your sending number is something that should be avoided

A new sending number requires it’s reputation to be rebuilt using a sending number warm up.

Frequently Asked Questions

Below are some frequently asked questions about SMS marketing carrier violations.

Who are the common phone carriers?

The term “carriers” in the US is used to describe AT&T, Verizon, T-Mobile and a number of smaller regional carriers.

Can someone opt-in if they’ve previously opted out?

Yes, but the mobile number will have to initiate this by sending in JOIN, SUSCRIBE, or another keyword approved by the carrier for signing up for text messages.

How can I find out what carrier a number belongs to?

To look up the carrier, along with other information, that a given number belongs to you can use a service like Really Good Data. They provide you with information about the carrier and if the number is mobile capable or not.

What is snowshoeing?

Snowshoeing is buying multiple long code (10 DLC) numbers to send from. While not illegal its is a practice that is generally frowned upon. Instead, consider registering your brand for 10DLC.

What is 10DLC registration?

10 digit long code (10DLC) registration is a process introduced by the carriers to allow businesses to register their 10 digit sending numbers.

Why is the carrier blocking my message?

To protect mobile customers carriers filter text messages that they identify as potential being harmful to consumers. They try to identify spam, fraud attempts, and abusive messages before they reach consumers.

Should I send messages using an email gateway?

An SMS to email gateway is an email address provided by the carriers that allow you to send an email that is then delivered as an SMS or MMS. We recommend avoiding using these email addresses to send text messages.

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