U might be able to route the call out on another trunk. Many companies have two providers for outgoing trunks so if one provider is having trouble, then possibly the other trunk would be working.
Taping in at the CO line is always a good idea to narrow down the problem. You won't get that message, but sometimes you will get another message if you sending out the wrong digits to the CO or if the line is configured incompatibly.
Da-vi'do Juan-is'imo
P.S. For the best response to a question, read FAQ222-2244. Also give the type & version of your voice mail & PBX & preview your post to make sure it is complete & understandable. Please answer all questions so that I may have the info to assist you. Leaving a post on how you fixed the problem will also be appreciated.