If there's a tree on 8892. The 2 extensions you need to record on are 5892 and 5893.
The greeting (press 1 for.... press 2 for....) on 8892 will be automatically generated when you set up the 58xx numbers.
The passcode on these 2 are set to 0000 and the tutorial is on.
To set up the greeting do this from a district phone:
5892 (or 5893)
and then follow the tutorial.
Let me know if you have any questions.