Fix HighLevel SMS Delivery Errors

Have you ever sent out a text campaign in HighLevel only to find that your messages never reached your contacts? Those little red triangles are more than just annoying—they signal issues that can affect your deliverability, compliance, and even your reputation.

SMS delivery failures are more common than you’d think, but the good news is they’re usually easy to diagnose and fix once you know what to look for. Whether it’s invalid numbers, user opt-outs, or unregistered sender IDs, this guide will help you decode those SMS errors like a pro.

Quick Takeaways

Most SMS failures stem from invalid numbers, spam-like content, user opt-outs, or missing A2P registration
HighLevel’s Conversations tab shows specific error codes to guide your troubleshooting
Verified numbers, clean content, and consent collection drastically reduce failure rates
SMS validation tools and proper number formatting improve deliverability
Avoid being charged for failed messages by resolving issues proactively

What Are Common Unsuccessful SMS Errors?

Unsuccessful SMS errors occur when your message fails to reach the intended recipient. This can happen for a variety of reasons—from technical restrictions and carrier filtering to invalid phone numbers or opt-outs.

In HighLevel, most SMS errors originate from carrier rules or issues with Twilio or LC Messaging infrastructure. These are flagged with specific error codes inside the platform, giving you the clues you need to troubleshoot the problem.

Key Benefits of Understanding SMS Errors

Understanding what these errors mean—and what causes them—is more than just troubleshooting. It’s part of building a reliable communication strategy. Here’s why it matters:

Better Deliverability
Knowing the most common reasons for failure helps you prevent them from happening in the first place.
Faster Troubleshooting
Error codes act like clues, allowing you to find and fix issues without guesswork.
Improved Compliance
Recognizing when and why messages are blocked helps you stay within carrier and legal guidelines.
More Effective Messaging
Cleaner lists, smarter content, and better sender IDs all contribute to higher engagement.

How To Identify and Interpret Common SMS Errors in HighLevel

Understanding what’s going wrong starts with knowing where to look.

Step 1 – Open the Conversations Tab

Head over to the Conversations tab in your HighLevel account. Locate the SMS thread that failed to send.

Step 2 – Find the Error Icon

Look for the red triangle icon beside the failed message.

Step 3 – Hover to See the Error Code

Hover your mouse over the triangle. You’ll see a short description of the error along with a numeric code like “Error 21610” or “Error 30007.”

This code tells you exactly what kind of problem you’re dealing with—whether it’s an opt-out, blocked number, or registration issue.

The Most Common HighLevel SMS Errors and Their Fixes

Here’s a simplified breakdown of the most frequent SMS delivery errors inside HighLevel, what they mean, and how to solve them.

Media Message Too Large

If you’re trying to send a video or image and it fails, chances are the file size is over the carrier limit.

Fix it: Resize or compress the file to be under 5MB.

User Opted Out

The recipient has previously unsubscribed by replying with “STOP.”

Fix it: They’ll need to send “START” to your number to re-opt in. Never attempt to resend unless they do.

Incompatible Number Pair

Your sending number can’t reach the recipient due to country or carrier limitations.

Fix it: Use a local or internationally-enabled number depending on your recipient’s location.

Suspended Twilio Account

Your account with Twilio may have been paused due to billing or compliance issues.

Fix it: Contact Twilio support and resolve the suspension before sending additional messages.

Inactive or Switched-Off Number

Messages sometimes fail because the recipient’s phone is temporarily off or unreachable.

Fix it: Try again later. If it continues to fail, verify if the number is still active.

Carrier Blocked Message

The content of your message triggered carrier spam filters.

Fix it: Avoid spammy content like all-caps, exaggerated claims, or shortened links. Always include your business name for credibility.

Landline or Non-Mobile Number

Landlines cannot receive text messages.

Fix it: Use HighLevel’s number validation to scrub your contact list before messaging.

Carrier Filtering (Spam Trigger)

Messages can be silently blocked if carriers flag them as spam.

Fix it: Use conversational, personalized messaging. Avoid generic promotions and register your number with A2P 10DLC.

A2P 10DLC Not Registered

You’re sending from a U.S. 10-digit number that’s not associated with a registered messaging campaign.

Fix it: Complete your A2P 10DLC registration via Twilio Trust Hub and associate your number with an approved campaign.

Unknown Error

Sometimes there’s no clear reason for a failure, and you’ll see a generic error.

Fix it: Try modifying the message content, test with another number, or contact support if it persists.

HTTP Media Retrieval Error

This often happens when trying to send an image or media hosted on a misconfigured domain.

Fix it: Make sure your DNS settings point your domain to brand.ludicrous.cloud. Use MXToolbox to confirm your CNAME records.

SMS Pricing in HighLevel (LC Phone or Twilio)

Understanding your messaging costs helps avoid surprises—especially when failed messages still incur charges.

Service	US/Canada Pricing
Outbound SMS	$0.0079 per segment
Inbound SMS	$0.0079 per segment
Outbound MMS	$0.0200 per segment
Inbound MMS (Local)	$0.0100 per segment
Local Phone Number	$1.15 per month
Toll-Free Phone Number	$2.15 per month
Phone Validation Lookup	$0.005 per check

Note: A single message may span multiple segments depending on length and characters used.

Pro Tips to Reduce SMS Failures

Validate phone numbers to weed out landlines and inactive contacts
Register your number under A2P 10DLC or use a verified toll-free number
Avoid spam triggers like excessive caps, emojis, or misleading sales language
Use clear opt-in processes to ensure your contacts want to hear from you
Set up alert workflows to monitor and respond to SMS failures in real time

Frequently Asked Questions

What should I do if a user has opted out?

They need to text “START” to your number to resubscribe.

Can I retry a message that failed due to spam filtering?

Yes, but edit your content first—remove any flagged phrases or formatting issues.

Can I get alerts for failed messages automatically?

Yes, create a workflow that triggers internal notifications or tags when a message fails.

How do I know if a number is a landline?

Use HighLevel’s phone validation feature or external lookup tools.

Why does HighLevel charge for failed messages?

Once a message is queued for sending, it incurs a charge—even if delivery fails.

Conclusion

Understanding SMS errors isn’t just a tech task—it’s a growth strategy. When your messages consistently land in your customers’ inboxes, everything from engagement to revenue improves. By taking a few proactive steps like validating your lists, registering your numbers, and cleaning up your content, you can minimize message failures and maximize your results.

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