Hi there and welcome
Is this for a Panasonic phone system?
1 minute as I upload the manual for you
The manual is here for you
On page 39 it will show you how to change the outgoing (greeting) message
If you have any problems, or would like any additional information or assistance, please do not hesitate to let me know.
And if you can take a second to rate my service by clicking one of the stars at the top of the screen then submit, that would be greatly appreciated.