When a text message fails to send or deliver in Aesthetix CRM, the conversation shows a numeric error code from the underlying Twilio messaging network. Each code points to a specific cause, such as an invalid number, a recipient who opted out, carrier filtering, or a registration that isn't complete yet. Use this reference to look up any code you see, understand what it means, and resolve it quickly so your patient messages keep going through.
This applies to SMS and MMS sent from your Aesthetix CRM phone numbers, whether sent manually from the Inbox or automatically through a workflow.
When a message fails, Aesthetix CRM displays the error directly in the conversation:
Open the Inbox and find the contact whose message failed.
Locate the failed text. A red triangle or error indicator appears next to it.
Hover over the error indicator. A small dialog shows the numeric error code and a short description (for example, "Error 30034" or "Error 21610").
Once you have the code, find it in the reference table below.
Code | What it means | How to fix it |
|---|---|---|
11200 | HTTP retrieval failure — usually an image that won't load or send in a conversation, caused by a misconfigured branded domain. | Confirm your branded media domain's DNS is set up correctly. If the CNAME record for your domain is missing or pointing to the wrong host, images appear broken. Correct the DNS record so the branded domain resolves, then retry. |
11751 | Media (MMS) message size limit exceeded — the attached media is too large. | Compress or resize the file. MMS to US/Canada numbers must stay within a 5 MB per-message limit. |
21211 | Invalid "To" phone number — the recipient number isn't valid or is formatted incorrectly. | Use E.164 format: [+] [country code] [number including area code], e.g. +15551234567. Confirm the correct country calling code, check for typos, and don't text a number to itself. Short codes and alphanumeric sender IDs cannot receive messages and shouldn't be used as a "To" number. |
21408 | Your account isn't enabled to send SMS/MMS to this country or region. | This guardrail prevents unexpected charges by limiting sends to regions you operate in. If you need to message a new region, contact Support to enable it. (Note: messaging to certain regions, such as Iran, is blocked for regulatory reasons.) |
21606 | The "From" number isn't a valid, message-capable number for this account or destination. | Confirm the sending number is SMS-capable under Settings → Phone Numbers, is in E.164 format, and belongs to your account. If the number is still being ported or hosted, wait until the transfer is fully complete. For short codes, the sender and recipient must be in the same country. |
21610 | The recipient has opted out — they replied STOP (or another opt-out keyword), or the contact has Do Not Disturb (DND) enabled. | You can't message this contact again until they reply START (or another opt-in keyword) to re-subscribe. Remove unsubscribed numbers from your lists, and always confirm consent before messaging. The number may also have been reassigned to someone who never opted in. |
21612 | The message can't be sent with the current "To"/"From" combination — often an international routing or sender-restriction issue. | Re-submit both numbers in E.164 format. Use a local number from the destination country where possible, or a number enabled for international sending. Some countries restrict which sender types are allowed; if the destination still won't route, contact Support. |
21614 | The "To" number isn't a valid mobile number — usually a landline or an invalid number. | Verify the number is a mobile number in proper E.164 format. Remove landlines from your lists. Some specialty numbers (IoT/machine-to-machine) use non-standard formats; if you believe a valid number is being rejected, contact Support. |
21635 | The "To" number is a landline and can't receive SMS. | Remove the landline from your list. If you're certain the number is a mobile number, contact Support. |
21661 | The "From" number isn't SMS-capable. | Open Settings → Phone Numbers to confirm the sending number has messaging enabled. If it doesn't, send from an SMS-capable number or add one. |
30002 | The account was suspended after the message was queued but before it was sent. | This can result from a billing issue or a policy violation. Contact Support to review and restore account status. |
30003 | The destination handset is unreachable or out of service — switched off, no signal, or otherwise unavailable. | Often a temporary issue — retry later. Confirm the device is powered on, has signal, and can receive other texts. Repeated 30003 errors on messages from regular numbers or toll-free numbers can indicate carrier filtering. If it persists, collect 3 or more examples from your message logs in the last 24 hours and contact Support. |
30004 | The message was blocked by the carrier — the recipient opted out, has DND enabled, or the carrier blocked delivery. | Confirm the number is valid and the recipient hasn't opted out. Avoid messaging numbers with a history of failed delivery. For persistent cases, collect 3 or more examples from the last 24 hours and contact Support. |
30005 | The recipient's number is inactive, unknown, or no longer exists. | Double-check the number is correct and in E.164 format. Clean your lists to remove inactive or unreachable numbers. If valid numbers keep failing, collect 3 or more examples from the last 24 hours and contact Support. |
30006 | Landline or unreachable carrier — the destination can't receive the message. | The number is likely a landline or otherwise can't receive SMS. Remove landlines from your lists and confirm numbers are SMS-capable before messaging. |
30007 | Message filtered — the carrier or messaging network blocked the message for appearing spammy or non-compliant. | Review message content and compliance: secure opt-in, identify your practice as the sender, include opt-out (STOP) language, and avoid public URL shorteners. See the section below for full prevention guidance. If you're confident your messages are compliant, collect 3 or more "undelivered" examples with error 30007 and contact Support. |
30008 | Unknown error — delivery failed for reasons the carrier didn't specify. | Try sending a shorter message with simple content and no special characters to rule out encoding issues. If it persists, collect 3 or more examples (no older than 48 hours) and contact Support. |
30011 | MMS isn't supported by the receiving number in this region. | On outbound messages, the recipient's device doesn't support MMS or has it disabled. On inbound messages, MMS isn't supported in that region — reply by SMS to let the sender know you can't receive their MMS. |
30023 | Daily message cap reached — you've hit the maximum daily messages allowed for your brand by the carrier. | This limit applies per registered brand (per EIN) across all outbound segments to certain carriers. Contact Support if you need help with your volume. |
30024 | Numeric sender ID not provisioned on the carrier — required in some countries that mandate pre-registration. | If you believe your sender ID is already registered, collect at least 3 message IDs showing "undelivered" with error 30024 and contact Support to review the registration status. |
30032 | Toll-free number hasn't been verified — required to send to US/Canada mobile numbers. | Toll-free numbers must complete verification before they can send. Aesthetix CRM handles toll-free verification on your behalf; contact Support if your toll-free messages are blocked. (Messages from unverified or pending toll-free numbers are blocked.) |
30033 | US A2P 10DLC campaign suspended — your message came from a suspended campaign. | Contact Support to find out why the campaign was suspended and how to resolve it. |
30034 | The number isn't fully registered for A2P 10DLC messaging — the brand/campaign may be approved, but carrier provisioning isn't complete. | After A2P approval, carrier-level registration can take up to 24 hours. Wait the full window before sending, and avoid test sends during that time. If the error remains after 24 hours, contact Support with your registration and number details. |
30037 | Outbound messaging is disabled for this account. | The account is configured not to send outbound messages. If you believe this is in error, contact Support. |
Carrier filtering (Error 30007) is the most common reason compliant-looking messages get blocked. Carriers filter messages that appear unwanted, spammy, or non-compliant — to protect consumers and enforce regulations like A2P 10DLC in the U.S. The guidance below helps your patient messages reach their destination.
Only message patients who have explicitly opted in.
Every message should identify your practice as the sender and include opt-out instructions.
Include STOP language at least once every 30 days if you message the same patient regularly. (Conversational, patient-initiated replies don't need STOP language in every message.)
Avoid creative opt-out variations like "Reply 2 to unsubscribe" — these are non-compliant and get filtered.
Reconfirm opt-in every 18 months to avoid messaging recycled numbers.
Monitor opt-out rates and complaint spikes — carriers begin filtering traffic that shows abuse patterns.
Avoid forbidden use cases (for example, payday loans, debt relief, cannabis).
Don't spread the same campaign across many numbers ("snowshoeing") to dodge filters — use numbers based on your location or business unit only.
Refer to SMS guidelines for any international destination you message.
Avoid public URL shorteners (Bitly, TinyURL). Use branded links on your own domain (for example, yourpractice.com/offer), and only the links registered with your A2P campaign.
Never use obfuscated links or suspicious redirects, and limit redirects to one.
Use clear, well-written language. Avoid excessive emojis, ALL CAPS, excessive punctuation, misspellings, and poor grammar.
Never send illegal, misleading, or forbidden content.
Process Do Not Disturb (DND) requests promptly — opted-out numbers are no longer valid recipients.
A message that triggers 30007 can automatically mark a contact as DND.
For more on managing opt-outs and consent, see the Do Not Disturb (DND) article and the A2P 10DLC registration article.
If your messages meet all compliance criteria but are still blocked:
Gather 3 or more contact examples from the past 7 days that show error 30007.
Share the contact links with Support for review.
To copy a contact link: open the Inbox, search for the affected contact by name or number, click the contact to open their details, and copy the browser URL.
A few habits prevent most delivery errors before they happen:
Use verified sending numbers. A2P 10DLC and verified toll-free numbers go through a vetting process that improves delivery and reduces filtering.
Format content properly. Avoid all caps and spammy phrasing, and keep links to your registered branded domain.
Keep lists clean. Make sure numbers are valid, in E.164 format, SMS-capable, and that contacts have opted in.
Monitor trends. Watch your delivery reports for recurring error codes so you can fix patterns early. You can also set up a workflow to alert you in real time when messages fail.
How do I get a patient to re-subscribe after they opted out?
They must text the word START (or another opt-in keyword) to the same number they unsubscribed from. You cannot re-subscribe them on their behalf.
Can I resend a message that failed with a 30007 error?
Yes, but revise the content to comply with carrier filtering guidelines first — otherwise it will likely be filtered again.
Why do some messages fail even when the number is valid?
Carriers may still block messages due to content filtering or the recipient's own settings (such as DND or a prior opt-out).
How can I tell if a number is a landline?
Landlines can't receive SMS and will return errors like 21635 or 30006. Scrub your lists for landlines before importing contacts.
Why does filtering vary between carriers?
Each carrier uses different filtering logic. A message blocked by one carrier may be delivered by another, depending on content, volume, and sender history.
Do I need A2P 10DLC registration if I only send to a small list?
Yes. Any U.S.-bound SMS traffic must comply with A2P 10DLC registration, regardless of volume.
Will Aesthetix CRM alert me to frequent SMS errors?
You can review delivery reports at any time, and you can build a workflow to notify you automatically when messages fail.
