Just a few questions to get me started - OmniPCX??, OMC

[Scoobs]

I have 3 Alcatel OmniPCX's on the bench (well I think thats what they are)
I hoping my ??s don't directly relate to actual models

2 x 1ru - 4 trunks, 4 analogue exts, 12 digital
1x 2ru - 12 trunks, 4 analogue ext, 12 digtial
using OMC to configure

Im working on learning as much as possible before my employer sends me to a course

My background is electrical/data/telecommunication cabling and infrusture
and quailified in other related areas (but very limmited to actual phone system programming)
I believe I just need somebody to throw me a bone in some basics on these systems and not question my speelling!

First - Is there someone that can explain what COS link is and/or how it used

I have a customer who has 5 bussiness at one site - each only 2 lines (one phone system for the whole site)
each office (1 bussiness) will have 1x analogue cordless and 1x digital (4029)
one office has a 4039
there will be one "common" handset (in the shared kitchen) that will ring for all incomming calls that are not picked up

GB and VM turned off as all calls will be diverted to mobiles in restricted mode (divert will be by telestra *21 access - as not to tie up the second line in the trunk. as it will be needed to recieve faxes)

the issue is - each office will only have access to their own trunk group and can not call/recieve on other office lines. but internal calls to all exts available

I need to configure eg. Dial 1 in office 1 - access to trunk group 1 only
Dial 1 in office 2 - access to trunk group 2 only
etc

yet the kitchen phone have access to all trunk groups
I belive I have the OMC softeware just about sorted out
Abled to configure trunk groups, hunt groups, AA, VM, Dyn Routing etc
and most other "basic" stuff

So my prob is understanding Link COs, Barring matix, sharring etc

Is there anyone that can provide a little how these above mentioned relates to trunk, subscriber access (I don't think i need a step by step how to do it guide) just a little push in the right direction (I have tied to OMC help but the penny has just not dropped)

anyhow any help is always a.... umm... help
Im hoping you don't say wait till you go to class....I don't want to be the one in the back asking ALL the questions!