| Hey alien, until recently I was a trained Siemens Hicom/Plessey ISDX-l person. I have done an Alcatel 4400 PCX 5-day course and did not find it too hard to pickup (I'll be doing a second 5-day course in October).
Not sure what the avaya is like, but I was used to command line programming with the Hicom and ISDX where as the 4400 uses a tool called 'mgr' which is menu driven (not GUI) if you go with the flow you soon get used to it. Sometimes I find it frustrating when you have to drill down the menu, where as on the Hicom I could just put in a command that I know to make a change. There is also a GUI tool '4730' & '4760'.
'mgr' example
__Users_________________________
| |
| -> Go down hierarchy |
| Consult/Modify |
| Create |
| Modify |
| Delete |
| FORCED DELETE |
| Memory re-initialization |
| |
________________________________ |