That being said
Decide what Ip address range you are going to use (autoconfigured, static or DHCP)
if you are trying to use static IP addresses the way that i have found is to set up a DHCP server (somehting like a ADSL router) on a non-customer netowrk that will issue DHCP addresses to the devices in the correct range. You can then use your laptop to change the address to a static one. (if I tried to change the range without going through the DHCP stage I had problmes)
Also check that the software build is the latest (certain features don't work until teh later releases). Groups don't have voicemail - only users do...
Practice upgrading and downgrading systems in the office before you go to site.
Docs and software are all available on the Avaya support site
Don't forget that One-X is designed to be user installable
Take Care
Matt
If at first you don't succeed, skydiving is not for you.