Error codes in VertexSMS API are global for all callbacks (requests we make to you) like sms delivery reports, home routing lookup reports. API calls (requests you make to us) errors are based on http headers, more info here
No error occurred.
Error from MSC, illegal subscriber.
Message not delivered - validity period expired.
Country or operator you trying send to, has not been configured for your account.
SMS is blocked by filter ex.: number blacklisted. If you get this error and would like to get more details, please contact us firstname.lastname@example.org
Limit of max SMS to one number reached
Account balance limit reached
The HLR responded with an error indicating the subscriber is unknown, probably don’t exists in operator database, it’s normal to repeat check for this subscriber after some time, and if you get this error again, MSISDN probably is not in use anymore.
The HLR responded with an error indicating the SMS service is barred for the subscriber. You can get this error if operator blocking P2P SMS traffic to MSISDN.
The HLR responded with an error indicating the subscriber is absent. Subscriber probably is out of the network range or the phone is turned off.
Other/unknown HLR error, please contact VERTEXSMS support for more information.
Unknown error from VERTEXSMS API