|Quoting FRAEDDF (Reply 46):|
I think it says "Servus", a greeting that is very common in Austria.
Indeed, especially in Eastern Austria (where Vienna is located), this is an extremely common way of saying "hi!". Using this word is actually even fairly common on ATC chatter in/around VIE: "leaving your frequency, servus!" is apparently not that uncommon, especially for OS planes.
But outside Austria, this word does not really mean anything, and hardly anyone will be familiar with it. Except if you had Latin at school, in which case it translates as "slave". Good going, OS marketing droids.
(but then, to expect a classical education from anyone working in marketing is probably asking way too much)