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Troubleshooting

SMS Messaging Errors

Last updated on 22 Sept, 2026

Detected Client Errors

A 4xxx code indicates that our telephony service provider or the downstream carrier has identified some element of the message request unacceptable. Repeating the request will produce the same result.

Code

Description

Explanation Of Error

4001

Message was rejected for reasons other than those covered by other 4xxx codes

This is a general error that the service you are attempting to use is not allowed; you may have inaccurate permissions, formatting or may not be enable to use that service.

4301

Malformed message encoding

The message contains invalid characters that are not supported. We cannot re-encode message for destination.

4302

Malformed From number

The From number associated with the message is a number not routable to a carrier or valid in the industry (Ex: a 9 digit number).

4303

Malformed To Number

The To number associated with the message is a number not routable to a carrier or valid in the industry (Ex: a 9 digit number).

4350

Malformed message encoding

Message passed validation on receive stage, but failed on send. This is likely because the destination number (To) is an invalid number.

4360

Message expired

Message was not sent because the specified expiration date passed before the message was able to send

4401

BW is unable to route the message

Message is unable to be routed by us for one of the following reasons:- The alphanumeric senderId is provisioned with an industry aggregator who is not in route;- The source and destination are the same;

4403

Messaging forbidden from sender

Messaging from this sender is forbidden, most commonly due to sender not belonging to us or the account. Other reasons may include:- The sender is not messaging enabled;- The account associated with this sender is not enabled for the type of message it is trying to send;- The sender is disconnected or inactive;- The sender is invalid(ex. 1111111111);

4404

Messaging forbidden on To number

Messaging to this To number is forbidden. This could be that the destination number is not active, not enabled for messaging, or is an invalid number (i.e. 11111111111). It may also mean one or more of the recipients in a group message is not valid(i.e. one of the recipients is a TFN orSC).

4405

Unallocated from number

The From telephone number is considered unallocated when the number does not exist in our database as an active number. This number is either not enabled for messaging at the industry level, or the number is not yet released in the industry

4406

Unallocated to number

The To number associated with this message, while a valid North American number, is not yet assigned to a carrier and the message cannot be sent downstream.

4407

From Number is associated with account

Undefined source account id. The From number associated with this message is not associated with this account, is an invalid number or not configured appropriately to send messages.

4408

To Number not associated with account

Undefined destination account id. The To (destination) number is not associated with an account, is an invalid number or not configured correctly to receive messages.

4409

Invalid destination profile

We failed to create destination. The destination profile is considered invalid, most often this is because the destination number does not support MMS.

4410

Could not download media

There was an error retrieving the media from the media web server. Check the media URL and try to access directly to see if the media can be fetched successfully.

4411

Combined size of media too large

The total size of MMS message media/attachments exceeded the max file size supported

4412

Failed to parse Content-Type for media

The media content type is not a supported media content type.

4420

No Route to Destination Carrier

The upstream carrier associated with the message does not exist in our configuration

4421

No Route to Destination Carrier

The message cannot be sent downstream as the account associated with the message does not have permission to send to this destination. You may not be provisioned to send to this destination.

4431

Messaging on shortcode forbidden

The message cannot be sent as the account associated with the message is not provisioned for Short code messaging

4432

Messaging to country forbidden

The senderId or account associated with this message in not enabled for messaging this destination country or the country is outside of messaging reach(specifically for MMS).

4433

Messaging on Toll Free Number Forbidden

The account associated with this message is not enabled for toll free messaging

4434

Messaging to Toll Free Number Forbidden

Messaging to this toll free number is not allowed. Number is likely not enabled for messaging or not active.

4435

Too Many Recipients

The group message has too many recipients. When sending Group Messages, there's a maximum of 10 participants in a Group.

4451

Invalid User Id

The user id is not a valid id. Verify the user ID and retry the message

4452

Invalid Application ID

The application ID specified is not valid. This may be due to the application not being associated with the account, or not associated with the sender.

4470

Rejected as SPAM

This message has been filtered and blocked by us for spam. Messages can be blocked for a variety of reason, including but not limited to volumetric filtering, content blocking, SHAFT violation, etc.

4475

Rejected due to user opt-out

User has opted out of receiving messages from a particular sender. Remove the destination TN from subscriber list and cease communication with the destination.

4476

Source TN is Unregistered

The source TN is not registered to a 10DLC campaign.

4481

From Number in black list

The From number has been flagged by us as prohibited from sending messages. This is typically because we or a downstream carriers has several violations; reports of spam, P2P violations, associated with this number.

4482

To Number in black list

The number you are attempting to send to is blocked from receiving messages.

4492

Message to emergency number forbidden

Messaging to an emergency number is forbidden

4493

Unauthorized

Our service indicates the sender is not authorized to send messages from the account.

Carrier Reported Client Errors

Code

Friendly Description

Explanation Of Error

4700

Carrier Rejected as Invalid Service Type

Carrier rejected message for invalid service type. This usually means messaging (SMS or MMS) is not supported by the carrier or handset. For RCS it means that the agent is not provisioned on the recipient mobile operator’s network.

4701

Destination is not reachable and SMS service is not available.

Carrier service is reporting the destination is not reachable or the SMS service is not available.

4702

Destination subscriber is unavailable.

This error indicates the subscriber is unavailable. There are several reasons for this; the subscriber has turned off handset, the destination is unreachable or barred, the GSM subscriber is busy for outbound SMS, SIM card is full, voicemail is full, or cannot reach the destination handset and has stored the message for retry in its « Store & Forward » function.

4710

Could not download media

There was an error retrieving media from the media web server. Check the media URL and try to access directly to see if the media can be fetched successfully.

4711

Media size too large

Downstream vendor cannot retrieve the media as the MMS attachment is too large

4712

The media content type is not supported

The media content type is not supported. Please review the accepted media types here.

4720

Carrier Rejected as Invalid Destination Address

Carrier Rejected as Invalid Destination Address. This could mean the number is not in the numbering plan (area code does not exist or the number is just invalid) or the number is not enabled for messaging (like a landline). Additionally, for toll free messages to TMobile, this could also mean the user has opted to block all toll free and short code traffic

4721

TN on deactivation list

The phone number you are attempting to send to is on the deactivation list. It is not associated with a carrier to be able to receive messages or is inactive.

4730

No route to destination carrier or no roaming route exists.

Carrier is reporting there is no route available for message. This could be because no routing exists to destination, no roaming route is available, the destination handset is roaming on a network that cannot be reached, no SS7 route, or routing was denied

4735

Too many destination numbers

Carrier is rejecting the message due to too many recipient addresses.

4740

Carrier Rejected as Invalid Source Address

Carrier is rejecting the message due to invalid source address - the number does not exist in the numbering plan. Other reasons for this error code is the source carrier is invalid or disabled or source not authorized or the number type is not supported.

4750

Carrier Rejected Message

The destination carrier has rejected the message but provided no specific reason. For AT&T traffic, this could be a prepaid user whose account is out of money, a subscriber that is provisioned to not receive this type of SMS or it was identified as Spam

4751

Message is too long or message length is invalid for the carrier.

Carrier has rejected for message length being invalid or too long. For messages destined to AT&T, messages with 10 segments or greater will be rejected.

4752

Message is malformed for the carrier.

Carrier is rejecting the message malformed; this could be because of a blank message, unacceptable data value, the receiving SMSC or SME does not accept messages with more than 160 characters, syntax error, content is invalid, message ID is invalid, invalid parameter length, expected TLV missing, invalid TLV value, invalid data coding scheme, invalid number of destinations, error in the optional part of the PDU body, TLV not allowed, or XML validation error.

4753

The destination handset has rejected the message

The handset has rejected the message

4754

Destination handset not supported

The destination handset does not support the channel being used to send the request. This may be due to the handset not being supported for RCS when being sent an RBM message.

4770

Carrier Rejected as SPAM

The Carrier is reporting this message as blocked for SPAM. Spam blocks could be a result of content, SHAFT violations (including specific keywords), originating address has been flagged for repeated spam content

4771

Rejected due to shortened url

There was an error with the shortened URL used. We recommend customers obtain their own dedicated domain if shortened links are needed for their messaging campaign.

4772

Blocked sender or receiver

This error indicates a blocked Sender or Receiver on the downstream platform. Please reach out to support so we can engage our vendor to determine which telephone number is blocked and why.

4773

Campaign inactive for destination

The campaign this TN is assigned to is not active for the destination. Please check the status with TCR (The Campaign Registry). You will receive this error if the campaign is pending or rejected by the DCA or suspended by an MNO but the TN is still assigned to the campaign.

4774

Issue with TN provisioning in industry database

There is an issue with how the number is provisioned in the industry's database. There may be some components of 10DLC provisioning that are incorrect or missing. Please reach out to support to investigate and correct this issue.

4775

Carrier Rejected due to user opt out

User has opted out of receiving messages from a particular sender. Remove the destination TN from subscriber list and cease communication with the destination.

4780

T-Mobile rejected due to volumetric violation

T-Mobile rejected due to volumetric violation. You have sent over the daily limit for your 10DLC Brand. Please review your Brand daily throughput limit to ensure you are not exceeding the approved volumes. To improve your Brand score please see our article on external vetting Brand Vetting.

4781

AT&T rejected due to 10DLC volumetric violation or throttling

AT&T rejected due to volumetric violation. You have sent over the rate limit for your 10DLC campaign. Please review your campaign throughput limit to ensure you are not exceeding the approved volumes. This error can also indicate throttling by AT&T for other reasons, including high spam rates.

4785

Carrier rejected due to volumetric violation

The carrier rejected the message due to a volumetric violation. You have sent over the allotted limit and need to back off sending. Please retry after some time.

4790

Carrier Rejected Due to Short Code Restriction

Carrier Rejected Due to Short Code Restriction. Destination address blocked by mobile operator, destination cannot receive short code messages, or the mobile operator blocked the destination from receiving messages from this short code for some other reason.

4791

Carrier Rejected Short Code Campaign Not Allowed

Carrier Rejected SC Campaign Not Allowed or blocked by the mobile operator

4792

Carrier Rejected Short Code Not Provisioned

Short Code not provisioned on mobile operator's network.

4793

Carrier Rejected Short Code Expired

Short Code expired with the mobile operator

4794

Message expired by carrier

Message expired with the mobile operator.

4795

Toll Free number is not verified

The message was blocked due to the toll free number not being verified. This can also be because there is SPAM on the unverified TFN. Please review unverified sending limits and submit TFN for verification as soon as possible.

Service Failures

A 5xx code indicates that either our telephony service provider or the downstream carrier has reported a service failure. For carrier errors a trying to send a message again might work, but we're unable to guarantee passing on the precise failure indicated by the carrier, but we do our best.

Code

Friendly Description

Explanation Of Error

5100

Application Error

An application within the our service is experiencing a temporary error that is preventing the message from being processed.

5101

Application Error

App going down. Message not received. Sender should send this messages later or to other host.

5106

Impossible to route / Attempt to deliver through retries has failed.

Impossible to route / Attempt to deliver through retries has failed.

5111

Application Error

Received messaged for connection which is already removed.

5201

Application Error

Our service expired the message after attempts to deliver through retries failed.

5211

Application Error

Our service application is temporarily busy so it cannot receive messages at this time

5220

Application Error

Message not received. Cannot save message to store.

5231

Application Error

We did not receive all parts of message. Message can not be sent.

5500

General Message Send Failure

The destination carrier has reported a general service failure with sending the message.

5501

General Message Send Failure

The message is unable to send as no destination is available.

5999

Unknown error from us

Unknown error generated by our telephony provider when we get an unknown error.

Carrier Reported Service Failures

Code

Friendly Description

Explanation Of Error

5600

Carrier Service Unavailable

Carrier Service Unavailable. This could result from network congestion, messaging queue full on the vendor side, throttling error on the vendor side.

5610

Carrier Service Failure

The downstream carrier application is experiencing an error. submitting the message has failed or cancelling message has failed

5620

Carrier Application Error

The carrier is reporting a general error associated with their application processing the message.

5630

Carrier Application Error

NACK - no response or acknowledgement received from the carrier

5650

Carrier Service Failure

Carrier Service is reporting a failure to send to destination (mobile operator or handset).

Carrier Errors with Ambiguous Cause

Code

Friendly Description

Explanation Of Error

9902

Timed out waiting for delivery receipt. The reason a delivery receipt was not received is not known.

Our telephony provider timed out waiting for the delivery receipt, this could be because the downstream provider did not send the requested delivery receipt or they sent after the system timed out at two hours.

9999

Unknown error from downstream. Carrier reported a failure code that is unknown to us.

We do not recognize the vendor's error response or does not have the vendor code mapped internally

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