SMS error codes dictionary

When an SMS fails to deliver, HoopAI logs an error code from the carrier or messaging provider. Use this reference to diagnose and fix delivery issues.

Common error codes

Code	Name	Meaning	How to fix
30001	Queue overflow	Message queue is full, message could not be queued	Reduce sending volume or spread messages over a longer period
30002	Account suspended	Your messaging account is suspended	Contact HoopAI support to review account status
30003	Unreachable destination	The destination number is not reachable (disconnected, out of service)	Verify the phone number is valid and active. Remove invalid numbers from your lists
30004	Message blocked	The message was blocked by the carrier or recipient	Check message content for spam triggers. Ensure A2P registration is complete
30005	Unknown destination	The destination number is unknown or improperly formatted	Use E.164 format (+1XXXXXXXXXX). Verify the number exists
30006	Landline or unreachable	The destination is a landline or cannot receive SMS	Remove landlines from your SMS lists. Use email instead
30007	Carrier filtering	The carrier filtered/blocked your message as spam	Register for A2P 10DLC, improve message content, reduce send frequency. See section below
30008	Unknown error	An unknown delivery error occurred	Retry the message. If persistent, contact support
30009	Missing segment	A multi-part message had a missing segment	Shorten your message or retry
30010	Message price exceeds max	Message cost exceeds account limit	Add funds to your wallet or increase the spending limit

Carrier filtering (30007) — deep dive

Error 30007 is the most common SMS delivery failure. It means the carrier blocked your message as suspected spam.

Common causes

No A2P 10DLC registration — local US numbers without A2P registration are heavily filtered
Content triggers — messages containing “free,” shortened URLs (bit.ly), or excessive caps
High opt-out rates — too many recipients replying STOP
Volume spikes — sudden increase in sending volume triggers carrier filters
No opt-in consent — sending to contacts who did not opt in

How to fix

Complete A2P 10DLC registration — this is the single most impactful step. See A2P registration
Use toll-free numbers with toll-free verification for higher throughput
Clean your contact list — remove invalid numbers, unsubscribes, and inactive contacts
Avoid spam trigger words — do not use ALL CAPS, excessive punctuation, or URL shorteners
Warm up sending volume — start low and gradually increase daily volume
Include opt-out language — always include “Reply STOP to unsubscribe”

A2P registration errors

Error	Meaning	Fix
Registration pending	Your A2P campaign is awaiting carrier approval	Wait for approval (can take 1–4 weeks). Check status in Settings
Registration rejected	Your A2P campaign was rejected	Review rejection reason, update your campaign details, and resubmit
Brand not verified	Your business brand has not been verified	Complete brand verification with EIN/tax ID documentation
Campaign suspended	Your messaging campaign was suspended for violations	Contact support, review compliance, and appeal

Blacklist and opt-out errors

Error	Meaning	Fix
21610	Contact has opted out (replied STOP)	Do not message this contact. They must reply START to re-opt-in
21611	Number is on the platform blacklist	The number has been flagged. Contact support for review
21614	Invalid “To” number	The recipient number is not a valid phone number	Verify and correct the number format
21612	Invalid “From” number	Your sending number is not valid or configured	Check that the number is active in Settings → Phone Numbers

Rate limit errors

Error	Meaning	Fix
Message rate limit exceeded	You are sending too many messages per second	Slow down your sending rate. Add waits between messages in workflows
Daily limit reached	You have hit the daily sending cap for your number	Wait until the next day or use additional numbers to distribute volume
Queue timeout	Message sat in queue too long without being sent	Reduce volume or contact support about capacity

For high-volume SMS, use toll-free numbers (higher throughput) or register multiple A2P campaigns to distribute load across numbers.

Troubleshooting steps

Check the error code

Go to Conversations and find the failed message. Click the error icon to see the specific error code.

Verify the number

Confirm the recipient’s phone number is valid, properly formatted (E.164), and not a landline.

Check A2P registration

Go to Settings → Phone Numbers → A2P Registration and verify your campaign status is Approved.

Review message content

Remove spam trigger words, URL shorteners, and excessive formatting. Keep messages conversational.

Check opt-out status

Verify the contact has not opted out (DND status). Go to the contact record and check the DND settings.

Contact support

If the issue persists after trying the above steps, contact HoopAI support with the error code and message details.

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Common error codes

Carrier filtering (30007) — deep dive

Common causes

How to fix

A2P registration errors

Blacklist and opt-out errors

Rate limit errors

Troubleshooting steps

​Common error codes

​Carrier filtering (30007) — deep dive

​Common causes

​How to fix

​A2P registration errors

​Blacklist and opt-out errors

​Rate limit errors

​Troubleshooting steps

Common error codes

Carrier filtering (30007) — deep dive

Common causes

How to fix

A2P registration errors

Blacklist and opt-out errors

Rate limit errors

Troubleshooting steps