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ADSL and phone joy - Ed's journal
ADSL and phone joy
Well, here's an oddity. Dad has ADSL at home. And it doesn't work.

Or it does.

Sort of anyway. We've been playing with it. If the house wiring isn't connected, then the ADSL works fine.

If the house wiring is connected, then it doesn't.

The master socket has extensions coming off it. If the extensions are disconnected, then the ADSL router connects, and ... well that's how I'm posting now.

If we connect up the wiring, then there's just no connection at all. As far as we can tell though, all the phones are fine. As is the wiring, and all the 'standard' phone lines are filtered.

It's a bit weird.

Anyone got any suggestions?
6 comments or Leave a comment
xarrion From: xarrion Date: December 29th, 2004 08:55 am (UTC) (Link)
Have you gone over your allowance?

IIRC home telephones have a Ring Equivalence Number of 4. Every device you hook up to a telephone socket has an REN. If you exceed 4, there isn't enough power for everything and nothing will work. I think a normal phone has a REN of around one.

Here's a quick google:
Ringer Equivalence Number (REN)

REN measures the load a device places on the line when ringing. A normal BT line will support a REN of at least 4, in other words at least a total of 4 phones/fax/modems should work on any line so long as their REN figures added together don't exceed 4. The REN is normally found on a label at the base of the machine (near the green approval symbol).

In practise you can quite often exceed this number because devices with an REN of 1 may actually have a real REN of only a fraction of 1. This is an anomaly of the test procedure used. Moreover many lines can drive an REN of more than 4. Note that some elderly fax and answering machines can have very high REN's (and they really are high!). If your phones all don't ring, or some ring very anaemically then its possible you have exceeded the REN. Try unplugging devices until they work. You can get REN Boosters which will increase the ringing capacity of a line if desired, although if you get to this stage you should probably be thinking of installing a small PABX.

dan_lane From: dan_lane Date: December 29th, 2004 09:47 am (UTC) (Link)
Unless you are heavily over your REN the only side effect of this is that none or only some of the handsets will ring.

REN boosters may actually introduce other problems on a line with ADSL enabled.
xarrion From: xarrion Date: December 29th, 2004 09:49 am (UTC) (Link)
We used to have a problem whereby if we plugged too much stuff in we lost the dialtone completely.
sobrique From: sobrique Date: January 1st, 2005 07:04 am (UTC) (Link)
That was indeed, the first thought. So we disconnected every phone in the house. To no avail.
dan_lane From: dan_lane Date: December 29th, 2004 09:44 am (UTC) (Link)
if all handsets are filtered (and all filters are assumed to be working correctly, they may be faulty!)... then the house wiring may be bad, it could be creating noise on the line that stops the ADSL syncing, isolate each extension and you'll find the offending one that can be excluded or rewired :)
sobrique From: sobrique Date: January 1st, 2005 07:04 am (UTC) (Link)
Even with all sockets/phones/filters disconnected we have the same problem.

Plugging the ADSL into the test socket works fine. Even tried putting a splitter into the test socket, running the ADSL from there. Works fine, right up until you reconnect the house wiring.

It's not _always_ a problem though. Just 95% of the time.
6 comments or Leave a comment