Who This Is For / When to Use
Users sending SMS or MMS messages from Kyrios Phone.
Teams troubleshooting undelivered or failed messages.
Account owners managing compliance, registration, and messaging limits.
How Phone Message Errors Appear in Kyrios
When an SMS or MMS message fails, Kyrios displays a plain-language error message directly in the conversation thread.
The message shows the error code and a short explanation.
A Learn More link appears for additional guidance.
Errors replace cryptic carrier codes with readable descriptions.
Common Phone Messaging Statuses
Delivered
The carrier successfully delivered the message to the recipient’s device.
Undelivered
The carrier rejected or could not deliver the message.
An error code and explanation are shown in the conversation.
Failed
The message could not be sent due to configuration, compliance, or carrier restrictions.
Action is required before retrying.
Phone Error Codes and Meanings
Each error code below can be resolved independently using the guidance provided.
Error 11751 — Media Size Limit
The attached media file exceeds the carrier’s size limit.
Reduce file size or send without media.
Error 30001 — Queue Overflow
Messages were sent too quickly.
Send no more than one message segment per second.
Error 30002 — SMS Capabilities Suspended
SMS sending is restricted due to a violation.
Contact your agency to restore sending privileges.
Error 30003 — Unreachable Destination Handset
The recipient’s phone is powered off or unavailable.
Retry later or use another communication channel.
Error 30005 — Unknown Destination Handset
The phone number is not recognized or no longer in service.
Verify the number before resending.
Error 21635 / 30006 — Landline or Unreachable Carrier
The number is a landline or belongs to an unsupported carrier.
Enable Number Validation to prevent sending to these numbers.
Error 30007 — Carrier Violation
Message content was filtered by the carrier.
Complete A2P or toll-free registration and review content guidelines.
Error 30008 — Unknown Error
The carrier did not provide a failure reason.
Monitor retries and contact support if it persists.
Error 30011 — MMS Error
The recipient’s device does not support MMS.
Send SMS only or confirm MMS capability.
Error 30019 — SMS Size Limit
Message length exceeds recommended carrier limits.
Keep SMS under 320 characters for best delivery.
Error 30023 — US A2P 10DLC Daily Cap Limit Reached
Daily carrier message limits have been exceeded.
Reduce volume or wait until the limit resets.
Error 30032 — Toll-Free Registration Pending
The toll-free number is not verified for US/Canada traffic.
Complete toll-free registration before sending.
Error 30034 — A2P Registration Pending
A US 10DLC number is not associated with an approved campaign.
Finish A2P 10DLC registration.
Error 21610 — Contact Opted Out
The recipient replied STOP.
Do not resend unless they opt back in.
Error 21211 / 21614 — Invalid or Non-Mobile Number
The number is invalid or cannot receive SMS.
Confirm the phone number format and type.
Error 21661 — Your Number Isn’t SMS-Capable
The sending number does not support SMS.
Use an SMS-enabled number.
Error 21408 — Region Restrictions on Sending
Messaging is blocked due to regional carrier rules.
Verify country and carrier permissions.
Common Issues and Fixes
Frequent undelivered messages: Check registration status (A2P or toll-free).
High failure rate on MMS: Confirm device compatibility and media size.
Carrier violations: Review message content and compliance requirements.
Invalid numbers: Enable Number Validation to prevent retries.
FAQ
What should I do if I see Error 11751 (Media Size Limit)?
Reduce the media file size to meet carrier limits, then resend the message.
How do I fix Error 30001 (Queue Overflow)?
Slow down sending speed and limit messages to one segment per second.
What does Error 30003 (Unreachable Destination Handset) mean?
The recipient’s phone is off or unavailable. Retry later or use another channel.
How do I resolve Error 30032 (Toll-Free Registration Pending)?
Complete toll-free number registration before sending messages to the US or Canada.
What causes Error 21211 or 21614 (Invalid or Non-Mobile Number)?
The number cannot receive SMS. Verify the number before resending.
Is there a recommended SMS character limit?
Yes. Keep messages under 320 characters to avoid carrier delivery issues.