Hi!
I tried it to see if I had the same problem and I had the exact same result you had...
It was pretty funny though because that extension is not in English so I got that message in another language and noticed that someone made a very bad translation...
They translated "bad" into "mean" (like a mean person) instead of the appropriate word for bad when when talking about something incorrect/wrong...
Now who ever heard of a "mean number"???? 
That must have been translated using Google translate or with something with a translation memory because I fail to see how someone could do that kind of mistake when they know that they are translating for a phone system...
Thank you for the giggles!
Nick