Hi All

I have a friend of the family who has signed up to Optusnet ADSL (don't ask me why) and he and I have installed the ADSL to his PC. Now to the issue of Line filters. I don't know a damn thing about line filters. We have a situation like this:

*** A CENTRAL LINE FILTER IS NOT AN OPTION ***

This is the setup of the phone system
http://users.tpg.com.au/clarke15/phonesetup.jpg

This is the line filters i received with the modem
http://users.tpg.com.au/clarke15/linefilter.jpg

A few questions:
1. Does the foxtel digital require a line filter? I assume the foxtel runs off the phoneline not the foxtel cable? Is this the case?
2. I attached one of these line filters to the phone in the computer room and the modem. I heard interference when i picked up that phone. Shouldn't it have been filtered even though the others weren't?
3. Some websites say that I need a central line filter if i have more than 4 phones. Surely this doesn't have an engineering explanation but more of an economic one?

Yes I have googled it. My google searches did not cover all my questions.
Yes I have qgl searched it. They did not cover all my questions either.

I wouldn't run more than 3 devices off the one phone line.

I don't think you are even supposed to run that many without ADSL.

1. Yes it will. It uses a regular ole dialup modem to phone home.

2. If you hear interference, then the filter isn't functioning as it should.

3. Central filter/splitters are more for convenience though I could see some issues with them.

Also, you can attach 3+ devices if you so wish but its not assured to work and depends a lot upon the quality of your phone lines both on your side and Telstra's.

Okay then

Well then where's the best place to get a bunch of these line filters for cheap?

Jaycar and dick smiths i suppose... range form like 19 bucks or so i think...

And i think you'll find foxtel runs on adsl hunter... the foxtel should actually be wired upto the box/telephone in as such to the house directly not piggybacked off another conneciton... if the tech wasn't lazy

The easy answer is any other device connected to the phone line needs to go through a line filter.
so, every single phone/fax etc will need its own line filter.

You can get a central one etc but its a pain in the ass.

foxtel is cable not phone line?

last time i needed filters, i just called telstra and said i needed 1 more line filter... granted, i was with bigpond at the time (they were the only ones round with adsl), and they sent me 2 in the mail.

Your friend would do best to have a central splitter (filter) installed. This will be the optimum solution, though not the cheapest as it needs to be installed by an accredited (licensed) cabler. The labour is the expense. But hey, it's a once off and insignificant in terms of the life of the service. The installation cost varies depending upon how difficult an individual job is (roof access etc). The splitter itself is inexpensive.

Oops..Just saw your NO CENTRAL SPLITTER caveat.

The (cheaper) alternative is to place an individual external inline filter between the line and every phone unit.

last edited by MiNG at 08:08:22 29/Apr/05

Ok basically if you have more than 3 analog devices plugged into the phone line you need a central splitter... you could probably get away without having one but if you ever have any trouble with you're connection you won't get much support unless you unplug a couple of those devices. Also Foxtel Digital can cause problems with ADSL, im not sure what the fix is for it, you might want to ask Optus... basically i know this because evertime i log an ADSL fault with Telstra for one of our customers, Telstra ask if Foxtel Digital is installed on the line.

Foxtel Digital, for satellite at least, definately uses a normal dialup modem and as such if there is no filter it can and usually will interfere with DSL connections. I have also encountered something odd over the years having ADSL - sometimes filters will fail. Whether or not its due to corrosion, component failure or whatever, I do know they can fail without warning. Regarding filters, you can buy them from pretty much any electronics store though you will pay more at places like DSE or Tandy.

I have also noticed that even with filters, occasionally my ADSL will s*** itself if somebody picks up the cordless phones. ADSL connections will also suffer if a jack in the house is a bit dodgy - one of ours was a bit flaky and ended up causing all sorts of issues for me.

we sell them at work, Dlink = $19.xx Netcomm = $21.00 (officeworks, garden city)

The whole "You shouldn't have more than 3 devices on the line" has to do with the phone line's load capacity and the TAM (i think) value of each device. A Telstra line can support 4.0 "worth of" load, most phones = 1.0, so 4 phones = line at max capacity, a lot of phones and faxes etc.. will have their load on them.