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Error Code Directory

Messages not being delivered? Check out the most common errors and how to troubleshoot them.

Sam Abello avatar
Written by Sam Abello
Updated over a week ago

Below is a list of the most frequent errors received when attempting to send messages with Grayscale. Hover over the❗️Not delivered message and find ERROR CODE to better understand why your message wasn't delivered.

Error Code Directory


12400

Internal Failure

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An internal error has occurred that prevented us from processing your response.

Possible Causes

  • An unexpected issue has occurred.

Possible Solutions

  • If the error persists, please contact us to figure out what has happened and how to fix it.

  • Note the time of the error and what you were trying to do when it occurred.An internal error has occurred that prevented us from processing your response.


21211

Invalid 'To' Phone Number

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You attempted to initiate an outbound text message, but the Message Sent phone number you supplied was not a valid phone number or was incorrectly formatted. Grayscale accepts phone numbers in E164 format: [+] [country code] [subscriber number including area code].

This error will also occur if you attempt to send a message from a Grayscale phone number to itself (i.e. putting the same Grayscale number in the To and From parameters).

Possible Causes

  • The formatting of the 'To' number you supplied was invalid.

  • You attempted to send a message from a Grayscale number to itself.

Possible Solutions

  • Ensure you have formatted your phone numbers in E164 format: [+] [country code] [subscriber number including area code]

  • Ensure you are not attempting to message from a Grayscale number to itself.


21408

Permission to send an SMS has not been enabled for the region indicated by the 'To' number

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You have attempted to send an SMS to a region that has not been enabled in your account's settings. These settings exist to help you ensure you only send SMS to the countries or regions you operate in, and avoid unexpected charges.

Possible Causes

  • You have attempted to send an SMS to a region that has not been enabled in your account's settings.

Possible Solutions

  • If you wish to send messages to this region, please reach out to your Customer Success Manager for assistance.


21610

Attempt to send to unsubscribed recipient

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The person you are trying to message has opted out of receiving messages from your team.

You have attempted to message a 'To' number that has replied with "STOP" to one of your previous messages. You will not be able to send to the phone number specified in the 'To' parameter until the subscriber identified by the phone number has responded with "START".

Please see this FAQ for more information about how Grayscale handles opt-out and opt-in.

Possible Causes

  • The end user handset has responded with "STOP" or another opt-out keyword.

Possible Solutions

  • Consider removing this phone number from your list of recipients.

  • Request the recipient to resubscribe to your messages by texting in "START" or another opt-in keyword to your Grayscale sender.


21612

Message cannot be sent with the current combination of "To" and/or "From" parameters

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You have attempted to send to a number that is not currently reachable via Grayscale SMS. If the number provided is a properly formatted E.164, it is most likely that Grayscale's communication provider does not yet have service with the carrier you are trying to reach. We have logged the carrier you are attempting to reach and will monitor these failures when adding new carriers. The combination of “To” and “From” parameters on this message cannot be connected by Grayscale at this time.

Possible Causes

  • Sender ID restrictions in the destination country: Many countries limit which numbers, short-codes, and/or alphanumeric senders can be used in that region.

  • Number formatting: The format you used for the “To” or “From” number may not be formatted using the E.164 format. Grayscale standardizes numbers using the E.164 format. If the “To” or “From” number of this message were altered by Grayscale in a way that you didn’t expect, try re-submitting the message with E.164 formatted addresses.

  • Destinations where Grayscale does not have connectivity: It is possible that Grayscale does not yet have service with the carrier you are trying to reach.

Possible Solutions

  • Consult the linked documentation for each cause. You can also try sending again with a different "To" and "From" combination.



21614

'To' number is not a valid mobile number

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You have attempted to send a SMS with a 'To' number that is not a valid mobile number. It is likely that the number that you have specified is a landline number or is an invalid number.

Possible Causes

  • The number you provided may be a landline number.

  • The number you provided may be invalid or formatted incorrectly.

  • If you are attempting to send SMS to Internet of Things (IoT) or machine-to-machine (M2M) numbers, the numbers may use a non-standard format that Grayscale has not added to our number validation system yet.

Possible Solutions

  • Confirm that the number you are sending to is not a landline.

  • Please verify you have provided a valid mobile number in proper E.164 format.

  • If you are attempting to send SMS to an IoT or M2M number, check whether the number format is different from the standard mobile numbers in that country or locality. Often, these numbers have additional digits or unusual formats which do not pass Grayscale's number validation. If you believe this is the issue, please contact Support for assistance.


21703

The Messaging Service does not have a phone number available to send a message

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None of the senders or numbers in your Messaging Service are capable of sending the requested message to this recipient.

Possible causes vary depending on the type of message and the country of the destination number. Below are several common causes of this error.

Possible Causes

  • You attempted to send a message to a United States or Canada mobile number, but you do not have any US/Canada numbers or short codes in your Messaging Service. US/Canada mobile numbers are not reachable from Grayscale numbers from outside the US/Canada, due to limitations imposed by carriers.

  • You attempted to send a message to a United States mobile number, but you do not have any long code numbers that are registered with a valid campaign. Only numbers registered for a campaign can be allowed to send to US based numbers.

Possible Solutions

  • Verify that phone numbers have been added to your bank of numbers by heading to your Grayscale Settings. All available phone numbers will be listed below your profile photo.

  • If there are no phone numbers listed, please reach out to your Customer Success Manager.



30003

Unreachable destination handset

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The destination handset you are trying to reach is switched off or otherwise unavailable.

Possible Causes

  • The destination handset you are trying to reach is switched off or otherwise unavailable

  • The device you are trying to reach does not have sufficient signal

  • The device cannot receive SMS (for example, the phone number belongs to a landline)

  • There is an issue with the mobile carrier

Possible Solutions

The first step to troubleshooting this issue is to attempt to replicate the problems. Attempt to send another test message to this user.

If you see similar results, continue troubleshooting with the following checklist:

  • Is the destination device powered on?

  • Does the device have sufficient signal? If not power the device off, wait 30 seconds, and then power it back up.

  • Is the device connected to the home carrier's network? We cannot guarantee message delivery on devices roaming off-network.

  • Can the device receive non-Grayscale SMS?

  • Can other devices using the same mobile carrier receive your messages?


30004

Message blocked

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The destination number you are trying to reach is blocked from receiving this message. Error - 30004

Message Delivery - Message blocked

Possible Causes

  • The destination number you are trying to reach is blocked from receiving this message.

  • The device you are trying to reach does not have sufficient signal.

  • The device cannot receive SMS (for example, the phone number belongs to a landline).

  • The destination number is on India's national Do Not Call registry.

  • There is an issue with the mobile carrier.

Possible Solutions

The first step to troubleshooting this issue is to attempt to replicate the problem. Attempt to send another test message to this user.

If you see similar results, continue troubleshooting with the following checklist:

  • Is the destination device powered on?

  • Does the device have sufficient signal? If not power the device off, wait 30 seconds, and then power it back up.

  • Is the device connected to the home carrier's network? We cannot guarantee message delivery on devices roaming off-network.

  • Can the device receive non-Grayscale SMS?

  • Can other devices using the same mobile carrier receive your messages?


30005

Unknown destination handset

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Possible Causes

  • The destination number you are trying to reach is unknown and may no longer exist.

  • The device you are trying to reach is not on or does not have sufficient signal.

  • The device cannot receive SMS (for example, the phone number belongs to a landline)

  • There is an issue with the mobile carrier

Possible Solutions

The first step to troubleshooting this issue is to attempt to replicate the problems. Attempt to send another test message to this user.

Pay close attention to your request and double check to verify you are attempting to send messages to the correct phone number in the correct E.164 format:

[+] [country code] [subscriber number including area code]

If you see similar results, continue troubleshooting with the following checklist:

  • Is the destination device powered on?

  • Does the device have sufficient signal? If not power the device off, wait 30 seconds, and then power it back up.

  • Is the device connected to the home carrier's network? We cannot guarantee message delivery on devices roaming off-network.

  • Can the device receive non-Grayscale SMS?

  • Can other devices using the same mobile carrier receive your messages?


30006

Landline or unreachable carrier

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The destination number is unable to receive this message. Potential reasons could include trying to reach a landline or, in the case of short codes, an unreachable carrier.

Possible Causes

  • The destination number is unable to receive this message. Potential reasons could include trying to reach a landline or, in the case of short codes, an unreachable carrier.

Possible Solutions

  • Verify that the candidate's phone number is accurate by checking their ATS profile details.


30007

Message filtered

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Your message content was flagged as going against carrier guidelines. Your message was filtered (blocked) by Twilio or by the carrier. This may be done by Twilio for violating Twilio’s Messaging Policy or Acceptable Use Policy, or by a wireless carrier for violating carrier rules or regulations.

Examples of messaging that would be blocked by Twilio are spam, phishing, and fraud. Twilio’s filtering system is in place to protect mobile subscribers from spam or other forms of malicious or unwanted messages.

Wireless carriers have filtering systems in place as well. These carrier filters are used to block abusive traffic, as well as to enforce rules or regulations about what types of messaging are allowed to that country or mobile network.


Possible Causes

  • Your message was identified as spam or unwanted messaging by Twilio's message filtering system

  • Your message was flagged as objectionable and blocked by a wireless carrier

Possible Solutions

  • Ensure your messaging use case complies with Grayscale's Messaging Policy.

  • Review the information in How Does Message Filtering Work? to understand what causes filtering.

  • See Field Guide for Avoiding Carrier Filtering for specific tips on avoiding message filtering.

  • If you believe your messages are compliant with Grayscale and carrier policies, please collect 3 or more examples of messages that have the “undelivered” status with error 30007, and then contact our Support team. We can help review your messaging and determine if an error was made, and put you in touch with our Compliance team if needed.


30008

Unknown error

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If a message you sent is not delivered to the end device and returns a 30008 error code, this means that delivery of your message failed for unknown reasons.

Possible Solutions

  • Check that the phone you were sending to is turned on and can receive non-Grayscale SMS

  • Ensure that the phone is not roaming off network. We cannot guarantee message delivery on roaming phones.

  • Try sending to other phones who have the same mobile carrier. If messages to other phones go through, the issue is likely device related. Try rebooting the device or contact the mobile carrier for help.

  • Try sending a shorter message to the phone, with simple content that does not include any special characters. This would give our support team an idea as to whether the failure is related to concatenation or character encoding.


30024

Numeric Sender ID Not Provisioned on Carrier

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Provisioning Issue with Carrier

You sent a message to a mobile number in a country that requires Numeric Sender ID pre-registration and provisioning. The Numeric Sender ID is not currently provisioned with the carrier.

Possible Causes

  • The Numeric Sender ID has not been provisioned by the carrier yet. Typically in this situation you would see >90% failures towards the carrier.

  • If this is for US A2P 10DLC and you just registered this number, it could take a brief period of time for all carriers to provision the number to your campaign. Typically you would see all messages towards a single carrier fail, if the code isn't provisioned.

  • The destination number has recently ported to a new carrier and the port hasn't completed 100%.

Possible Solutions

If you believe your Numeric Sender ID should be registered, please collect 3 or more examples of messages that have the “undelivered” status with error 30024, and then contact our Support team. We can help review the registration status to resolve these errors.


30034

US A2P 10DLC - Message from an Unregistered Number

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Messages sent to US numbers will not be delivered if they are sent from numbers that are not associated with an approved A2P 10DLC Campaign. To initiate a A2P 10DLC registration, visit Grayscale A2P 10DLC Registration. Find out how to register using this guide.

Possible Causes

  • You are sending messages to the US using a US 10DLC number that is not associated with an approved A2P 10DLC Campaign.

Possible Solutions

  • Reach out to Support to verify your account's registration status.


63016

Failed to send freeform message because you are outside the allowed window. If you are using WhatsApp, please use a Message Template.

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Possible Causes

  • This message failed to be delivered to the user because it was sent outside the messaging channel's allowed conversation window. For WhatsApp messages initiated by the business, you must use a pre-defined template.

Possible Solutions

  • Send a WhatsApp message using an approved template.


GS10088

The message template took too long to approve.

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Possible Causes

  • The format is incorrect, such as misplaced or malformed placeholders

  • The template breaks the WhatsApp terms of service, commerce policy business policy, or is seen as abusive

  • The template is too generic and has placeholders that could be used for abuse

Because placeholders can be replaced with multiple words, WhatsApp does not allow template placeholders to be placed at the beginning or the end of the message. Doing so will result in automatic rejection of the template.

Common Rejection Reasons

Rejection Reason

How to fix it

Snippets are placed in the very beginning or end of the message

Add additional words or punctuation before/after the snippet.

Snippets are placed next to each other, such as "{{ profile.first_name }} {{ profile.last_name }}"

Make sure there is at least one word in between each snippet, or simply use one snippet instead of multiple. You can substitute a placeholder value with multiple words.

Newlines, tabs, or more than 4 consecutive spaces

Per Meta's rules, this is not allowed, so please avoid.

Call-to-action have a direct link to WhatsApp, such as "https://wa.me/14154443344". Meta no longer allows this.

Spell out the number, without including the link. The wa.me is a reserved link that can't be included in a template.

Template is a duplicate. WhatsApp rejects templates submitted with the same wording with a different name, to prevent abuse. Please note that this check does not apply to OTP templates.

Slightly tweak the name and content of the new template

Template contains content violating the WhatsApp Commerce Policy or the WhatsApps Business Policy. Includes: requesting sensitive identifiers from users, such as payment card numbers, financial account numbers, or National Identification numbers.

You must follow WhatsApp's policies to avoid further enforcement action from Meta. If you need to request sensitive identifiers, you can ask for partial identifiers (ex: last 4 digits of Social Security number).

Templates appears to be related to gaming or gambling. Common words such as "raffle" or "win a prize" almost guarantee a template rejection by WhatsApp.

Identify any words that could remotely be perceived as related to gaming/gambling, and replace them.

Templates that are overly vague, such as “Hi, {{ profile.first_name }}, thanks”. are commonly abused to spam users, so they will be rejected.

Surround the parameters with information that clarifies to Meta what type of information will be inserted.


If you still have questions, chat with us below!

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