I resisted answering the question, because I don't really know, either. The message is certainly ambiguous. I think your translation is correct.
However, in context: if the OBi can make phone calls to various numbers, but only that one business number returns the error, then I believe it is telling you that the service provider (I mean, the SIP server supplying service to your OBi on the SPx slot you are using, e.g. Google Voice), sent a hello message to the called party's destination, but it did not receive a SIP message of some kind in return (no response from that number's service provider)...or, your ITSP (e.g. GV or Callcentric or whatever) itself is failing to make the call to the number you entered.
So: does your device work correctly, other than when trying to call a particular phone number?