1) No loop current/ AB (hang up in send) – This error indicates that the remote line disconnected the call with no error message or reason for the disconnection provided. When this error occurs, we mark the transmission as a failure. The first step in troubleshooting these errors would be to examine the failure that is causing the remote line to disconnect. They would need to examine call logs or contact their service provider for more information. Note in this case that if we do not receive any type of response for 30 seconds at any point during the transmission, we mark it as a disconnection. If the remote end is logging the error as a disconnection on our side, this is likely the case so their service provider would want to troubleshoot any issues that would cause a 30 second lapse in communication during the call.
2) Phone failed on global DNS Lookup – All numbers to be dialed are first cross-checked on a “Do Not Send” list. Any number that fails with this error is either on the list per the owner’s request (they requested we block dial attempts to their number), on this list per our security team (e.g. 1-900 premium-rate numbers), or the number is invalid and cannot be dialed. Typically invalid numbers have too many/not enough digits, are international but did not include the “011” international prefix, or contain an invalid sequence of numbers (e.g. “555” or “123” exchange).
3) Phone number failed to pass phone mask – Bad number or formatted wrong (needs to be an actual fax number with proper formatting)