Why do some of my Act-On SMS messages fail?

  • Updated

During your SMS campaigns, some messages may fail to deliver to the contact you're trying to reach. This can happen for a variety of reasons, including imperfect data and trying to send messages to a phone that isn't SMS capable.

Want to learn more about SMS and Act-On? See our guide here.

View the SMS Failed Messages Report

Visit your SMS Sent Messages Report to find a list of SMS message failures and the errors that caused them. To do this:

  • Go to SMS > Messages > Sent Messages
  • In the Sent Messages list, click on the SMS message you'd like to review
  • In your SMS message's report, click Failed

SMS Failed Send Details will show you the number of send failures for your SMS message. You'll also find a breakdown of error types, including the percentage of messages that failed due to a specific error. Below SMS Failed Send Details, you'll see a list of all recipients who didn't receive your SMS message, their phone number, and the reason that they did not receive your message.


Types of SMS errors

Reason for error Description
Landline The message tried to reach a landline phone, which cannot receive SMS.
Unreachable Destination

You're trying to reach a landline (see above) or a handset that is turned off/roaming.

Unreachable Carrier The subscriber's carrier does not support SMS messaging. This often occurs with pre-paid mobile devices or international sending.
Message Blocked The subscriber has blocked SMS messages from your sending number. No further action can be taken.
Unknown Destination

You might see this error when:

  • The mobile number no longer exists
  • There's a carrier outage
  • The device you're trying to reach is turned off/roaming
Unknown Error

We know – not very helpful! You might see this error if:

  • You're trying to reach localized regional mobile carriers that sell mobile in low population areas
  • The device or carrier you're trying to reach is unsupported
  • The subscriber's handset is turned off/roaming
Carrier Filtering

Your SMS message has been blocked by carrier filtering algorithms. Check your message's content and URLs for any potential violations.



Remove incorrect contact data

Currently, Act-On relies on you and your marketing team to ensure that your contact's data is accurate and up-to-date. We won't take any additional action when an SMS message fails to send because it's trying to reach a landline number. We recommend cleaning your data to keep it error-free. There are a variety of online data cleaning services available to help you do this.

Prevent carrier filtering

Due to the pandemic, 2020 was a banner year for spam. As a result, many carriers have cracked down on potentially spammy SMS messaging. Avoid the following to prevent carrier filters from blocking your SMS messages:

  • Over-capitalizing your messages
  • Overuse of special characters (such as $, %, or !)
  • Leaving out Reply STOP to opt-out at the end of your messages
  • Using Bitly, TinyURL, or other link shorteners
  • Including terms that apply to the exchange of money (such as loans, credit, gambling, or deals)
  • Including content that involves sex, hate, alcohol, firearms, tobacco, and illegal/legal drugs

Act-On will monitor these filtering errors. If you continue to receive a high volume of carrier filtering errors when sending SMS messages, please reach out to your Act-On Account Manager for assistance. We'll likely reach out to you first to discuss how you can mitigate these errors if we notice that your messages are being filtered. 

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