Gel wrote:
> I was always puzzled at the limit of 4 for REN, which was roughly 4
> phones/devices max, when you think about how many phones/gadgets we
> tend to have hung on line these days.
Typical actual RENs are really low, but the general public cannot cope
with decimals, or atleast that is what the manufacturers think. (Having
worked with the general public, I think the manufacturers are being a
bit optimistic assuming that they can add up to numbers as high as four
(I double as a betting shop manager, and cover fratton park on match days)).
> You've also answered one query as to why some phones will ring on a
> secondary socket {ie with no bell capacitor} and some won't.
You are supposed to connect wire 3 (orange) from master to secondary in
order to provide a ring signal for the benefit of those telephones.
It is also possible that pin 3 in your socket is actually pin 4, due to
the upside-down nature of the wiring standard. Pin 2 on the socket
actually mates with pin 5 of the plug, 3-4, 4-3, and 5-2. (Ditto pins
1+6 if you have them, which you probably dont). With such daft
standards, some manufacturers get confused. If you are looking at the
front of the socket with pins uppermost, pin 3 is either the 3rd or 4th
pin, depending on whether you have four (5432) or six (654321) pins in
your sockets.
If you are holding a plug with pins uppermost and facing you, the pins
read left to right in order (i.e. 123456 for BT631 plugs and 2345 for
the more common BT431 4-way plug)
Maddening, isn't it? A good (as in sanity-preserving) career move is to
pretend to know absolutely nothing about networking, computing, and
telecoms.
> Presumably further away from exchange you are the more critical the REN
> factor is as weaker signal.
It doesn't actually make that much difference, because the ring signal
(which is +/- 40 to 100 volts, with or without a DC bias (typically
48V), at 25Hz, line length is unlikely to affect it.
Too many devices on the line _may_ cause the exchange to see a lower
line resistance than normal, possibly causing a 'ring trip', although
this is really unlikely unless you go mad with the things. Ring trip
usually only occurs in the event of water ingress or some other fault on
the BT side of the circuit.
Line length does affect propagation of higher frequencies, such as those
used in DSL signalling. As of course does the general quality of the
line, type and age of wiring, the phase of the moon, the day of the
week, and whether or not dave the mad cable guy did your street's
wiring. (Every BT area has a 'Dave the mad cable guy' who may or not
actually be called Dave)
> I was told when I applied for ADSL I'd be lucky to get
> 512mb[due to distance from exchange}, since then I've got it to 1mb,
> and next month will wait to see if it achieves 2mb free upgrade.
I'm still waiting here. PlusNet have a page at
http://usertools.plus.net/exchanges/ which lists expected start dates
for particular DSLAMs which suggests I'll be waiting until August.
While I'm with Demon, everybody gets to use the same DSLAMs, and Demon
(and PlusNet) expect all work to be complete by September. If you just
assume that, you may be pleasantly suprised.