SMS error codes are sent at each stage of the delivery process. Depending on the message_state returned, an accompanying error_code may be given. That is, if delivery is unsuccessful when we tried to deliver the SMS to the carrier, the message_state would update from “queued” directly to “failed” and an accompanying error_code will be given. If the message has been successfully sent to the carrier, it can still hit roadblocks that can cause the SMS to fail. In this scenario, the message_state would change from “queued” to “sent”, then to either “undelivered” or “rejected”, which will also be accompanied by an error_code. In essence, SMS error codes can help you supplement your diagnosis of the delivery issues. Below is an illustration of the delivery success path and the message_states that can occur.

Process Diagram SMS Message States and Error Codes

Error CodeError ReasonDescription
10Invalid messageThe message content is blank or exceeds the character limit of 1600 for messages encoded with GMS and 737 for messaged encoded with Unicode. Note that while we provide a separate error code to indicate if a message is too long, some carriers only send an “invalid message” error and don’t differentiate between blank messages and long message errors.
20Network errorThe carrier delivering the text message had network issues. To resolve this, you can retry at a later time when the carrier network is unaffected.
30Spam detectedOne of the most common reasons for SMS delivery failure is carrier level spam filters. Carriers have added systems and algorithms that detect spam content and then block them before they even get delivered. Unfortunately, these filters are always hidden, subject to carrier preferences, vary from carrier to carrier, and can be changed without notice.

Another common reason why this error code could be returned is that you may have attempted to send too many messages using long code phone numbers in US & Canada. Long codes are 10-digit phone numbers and are intended only for peer-to-peer (P2P) communication. If this issue persists, we highly recommend using short codes for sending bulk messages within US and Canada. Visit our short code page to learn more about obtaining and setting up a short code for your campaign.

However, if you are confident that your message content is compliant, then retry sending the message again. You can also contact our support team to whitelist your message one time with our downstream carriers.
40Invalid source numberThe source number you entered is either not in the correct format, not SMS-enabled or not assigned to your Plivo account. Check the “src” phone number in your application and ensure that it is in the correct format and has the ability to send text messages. All phone numbers in your application should include country code, area code, and phone number without spaces or dashes (e.g., 14155555555 for US or +491155555555 for Berlin, Germany).
50Invalid destination numberThe destination number you entered is either not entered correctly, not SMS-enabled or is a PSTN landline. Check the “dst” phone number in your application to ensure that it is able to receive text messages. All phone numbers in your application should include country code, area code, and phone number without spaces or dashes (e.g., 14155555555). If you’re sending multiple text messages, make sure that the phone numbers are separated with the “<” character (e.g., 14156667777<14157778888<14158889999).
60Loop detectedThe carrier is not able to route your SMS because certain settings in your application are corresponding to an endless loop of messages being sent and received between your “src” and “dst” phone numbers. This can occur when two auto-responding SMS applications start to talk to each other and end up in a loop. Carriers detect loops by comparing messages within a predefined period of time to previous messages sent and received.

SMS loops can increase unnecessary spend, so to ensure that your applications do not trigger loops, it’s a good idea to create loop filters in your application because not all carriers have loop detection.

In some cases, this error code is returned when the carrier determines that it is impossible to route the SMS and the message has to be dropped as it is being looped between platforms.
70Destination permanently unavailableThe destination (i.e., “dst”) phone number is not active and there is no indication of when it will become available again. Note that this is a broad error code where the carrier has not indicated the reason for the destination unavailability. Check the “dst” phone number to ensure that it is correct. Also, try sending messages to an alternative number to ensure that all other parts of your application are working.
80Destination temporarily unavailableThe destination (i.e., “dst”) phone number is not reachable. Note that this is a broad error code and often times, the carrier does not indicate the reason for the destination to be temporarily unavailable. Though, possible reasons could be due to the handset being turned off or out of coverage. To resolve this, retry your messages at a later time.
90No route availableThe carrier and fallback carriers were not able to deliver the SMS message because the route was not available. Please note that carriers do not offer the reason for why the route is unavailable, but since this is typically a carrier issue, please contact us and include the message UUIDs of the SMS affected.
100Prohibited by carrierThe carrier rejected the text message because the network did not support the message being sent. This could occur if the destination network does not support SMS.
110Message too longThe message content exceeds the character limit of 1600 for GSM and 737 for UTF encoded messages. Note that depending on the byte size, Emoji characters can also increase the message character count significantly. Also, Plivo automatically concatenates messages longer than 160 characters for GSM encoded messages and 70 characters for UTF encoded messages. Check our FAQ on long message concatenation for more details.
200Source number blocked by STOP from destination numberThe destination has opted out from your campaign and blocked all messages sent from your phone number. Opt-outs are typically received via text message replies with a opt-out keyword including “STOP”. All messages to destinations that have opted out will be blocked until the destination opts in with another response. Check our FAQ to learn more about opt-out and opt-in processes.
201Outbound messages from US Toll-Free numbers to Canadian destination numbers are blockedYour application is attempting to send text messages from a United States Toll-Free phone number to a Canadian phone number destination. Unfortunately, carriers limit US Toll-Free phone numbers to only send SMS to US phone numbers.
1000Unknown errorDelivering your message failed for reasons that are unknown to us and to our carriers. If you notice too many of these cases, please open a support ticket with us so that we can help you identify the problem. Be sure to include the message UUIDs of recent messages (preferably within the last 72 hours) that have been affected.