In SMS.to Reports, you can easily track the status of your sent messages. The report will show you not only the messages that have been successfully delivered but also those that failed to reach the recipient.
Understanding why these messages did not reach the end recepient is crucial for optimizing your SMS delivery issues.
If the message has failed, you will be able to see the reason for the failure under the 'Status' column. For example:
Below, we’ve provided an overview of the common error codes you may encounter when a message fails, along with explanations for each:
| Error Code | Error Reason | Explanation |
1 | Unknown Subscriber | The “Unknown Subscriber” error typically originates from the Home Location Register (HLR) or the Home Subscriber Server (HSS) in GSM/LTE networks. The HLR/HSS is responsible for storing subscriber information (IMSI, MSISDN, services, roaming data, etc.). When an SMSC (Short Message Service Center) or signaling entity queries the HLR for routing information to deliver an SMS, the HLR returns Unknown Subscriber when:
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| 2 | Unknown Base Station | An unidentified or unrecognized base station, often in the context of network or communication systems. This could be due to a missing or inaccessible base station. Error 2 Full Description |
| 3 | Equipment protocol Error | Equipment protocol error. |
| 4 | Equipment not equipped for SM | Equipment not equipped with short-message (SMS) capability. Error 4 Full Description |
| 5 | Unidentified Subscriber | The destination number doesn’t exist or can’t be found in the network’s subscriber database. It’s a permanent, non-recoverable delivery error, usually requiring the sender or operator to validate or remove the MSISDN from active campaigns.Error 5 Full Description |
| 6 | Illegal Subscriber | The mobile station (handset) failed authentication Error 6 Full Description |
| 7 | Teleservice Not Provisioned | Teleservice not provisioned. Mobile subscription identified by the MSISDN number does not include the short message service. Error 7 Full Description |
| 8 | Illegal Equipment | IMEI Check failed, IMEI is either blacklisted or not Whitelisted Error 8 Full Description |
| 9 | Handset Memory Full | Handset memory capacity exceeded. Handset has run out of free memory to store new message. The only solution for that is to delete old and unneeded messages from your SMS inbox Error 9 Full Description |
| 10 | Unknown Equipment | The mobile device has not been recognized by EIR (Equipment Identity Register) during device verification on the MAP protocol level at the operator’s infrastructure. |
| 13 | Mobile Handset Switched Off | The mobile device is turned off or was turned off at the moment that the message was sent Error 13 Full Description |
| 16 | Absent Subscriber | Absent subscriber. No paging response via MSC. Error 16 Full Description |
| 17 | Absent Subscriber | Absent subscriber. IMSI detached. Error 17 Full Description |
| 18 | Absent Subscriber | Absent subscriber. Roaming restriction. Error 18 Full Description |
| 21 | Facility Not Supported | Not supported by the handset or the network being used due to limitations, restrictions, or incompatibility. Resolving this error typically involves:
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| 27 | Absent Subscriber | The destination numbers provided during the submissions were unreachable:
Error 27 Full Description |
| 30 | Subscriber Busy For MT SMS | Subscriber Busy For MT SMS |
| 31 | SMS Expired | SMS has expired after attempting delivery for too long |
| 34 | System Failure | System Failure |
| 35 | Data Missing | Data Missing |
| 36 | Unexpected Data Value | Unexpected Data Value |
| 37 | SenderID not Registered | SenderID is not Registered to that Network/Country, please contact support at : support@sms.to |
| 38 | Number not registered in network | Unknown subscriber: The number is not allocated. An Unallocated number is a valid phone number that does not belong to any subscription. There are two clear reasons for this.
Error 38 Full Description |
| 2001 | Blacklisted Destination Number | The destination number has been blacklisted either at the operator`s request or on your account via the SMS.to web interface. |
| 2002 | Blacklisted Sender Address | The sender number has been blacklisted either at the operator's request or on your account via the SMS.to web interface. |
| 3000 | Unknown Error | Error not yet mapped or not shared by provider/operator |