Error Code Directory

An unexpected issue has occurred.

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.

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

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

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

Ensure you have used the correct country calling code for the phone number you are calling.

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

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

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

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

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.

Before sending messages to a recipient, ensure they have consented to receive messages from you. Please read these guidelines to understand messaging opt-in requirements and best practices.

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.

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

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.

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.

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.

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.

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

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?

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.

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?

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

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?

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.

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

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

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.

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.

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%.

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

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

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.

Send a WhatsApp message using an approved template.