Hi all. I'm after a bit of advice re: how network phone systems work, in this case its the Avaya IP office system.

I'm currently doing an installation (I'm an electrician) in an office. I was told told to run a cat5 for network connection to each desk with a single rj45 outlet at the desk and to a patch panel in the server cupboard. Which I've done, easy.

Now the phone guys have turned up and installed their 'stuff' (I'm no expert when it comes to network phones) but it is a big box connected to the phone line with patch leads coming out.

They've connected the patch leads into my patch panel so now every desk has a phone connection through rj45 outlets I've fitted.

But now none of the desks have an Ethernet connection! Because the phone guys have stolen it 

The customer admits he should have asked me to wire 2 cat5's to each desk but its a bit late now the rooms been plastered so running more cables is not really an option.

I know you can 'get away' (read: bodge) Ethernet to run off just 2 pairs of the cat5 but will the network phones run off the other 2 pairs? Or do they need all 4?

Anyone have any experience in these?

Cheers

We run a mix of Avaya analogue and VOIP phones (primarily 1616 and 4610 VOIPs) at work, not sure how that equates to the phones your using but on the back of each phone is a 2nd RJ45 port which you plug the PC into so it can all run through one floor/wall port.

I do remember something happening where the port on the phone wasn't working unless some settings were turned on in the phone config files, but I can't remember what it was I think we got our telephoney support company to dial in and sort it!

That sounds promising.. I'll try and have a look at the phones that they're using.
Cheers

Like they say above, I wouldn't expect the phones to be directly connected to the PBX, the PBX should be connected to the switch, the same as the rest of the it on the network, then usually a pass though on the back of the phone to allow installation in to existing setups without running more CAT cable...

However in theory if for some reason that doesn't work then you could just connect 2 twisted pairs, although I'd test one first (just in case), however then any kit connected that requires all 8 wouldn't work.

Only consideration if they are connected directly to the PBX, then the phones may be PoE? Do the phones have their own power supply or powered over the CAT? May be able to link the PBX to the switch in this case, I'd assume the PBX guys would be the best people to ask though

Again I'm no expert, and had very limited experience of PBX in the past, but the ones I have used work as above..

hmmm the ip office wouldn't have an issue, however... just hope they are IP phones with ehternet through ports.
the IP office phone supports digital & analog phones, depending on what card is installed.

Personally, I would keep out of it. Let the owner sort it out with the phone installers. Otherwise you will try to be helpful & see it backfire. Especially if going the 4 cable route ends up having problems in the future. Phones can run on 4 wire if they are analog or digital - but that is for the phone installers to sort out with splitters.
At worst from an IT point of view, rather than fook around with the cabling & the office layout allows it, I would suggest some small swtiches or hubs.

I always run an extra cable when doing cable runs of 4.
Cable is cheap enough & it's always worth having a spare.
Might be worth considering next time you're on a job to explain the benefits.

if your the smaller company.
dont get involved.

You done what was asked for.

These things tend to end badly when trying to help & before you know it you have sunken lots of your own time & money into an issue that is another companies problem by not speccing up the right kit.

One cable is fine.

On the switch they will set

switchport voice vlan x
switchport access vlan y

And present 2 vlans. The phone and the PC will 'know' which to use. This is the normal way to roll IPT out.

Surely they are analogue phones if they require one cable per phone?

Not necessarily, the PBX is a modular box, you can fill it full of Ethernet ports and itself will act as a switch, either converged with the existing data network or with the intention being to physically separate from any existing network.

Look at the modules on the PBX to determine what handsets they are supporting.

He's talking about a single physical port for two devices, not network segregation. Sounds like the handsets are not IP anyway and connecting directly to the pbx..

Mark is describing Logical segregation at Layer 2, not physical segregation.