| From: | Matt Sealey |
| Date: | 25 Oct 2000 at 12:07:40 |
| Subject: | Re: ISDN to ASDL problem |
Hello Tudor
On 25-Oct-00, you wrote:
> On Wed, Oct 25, 2000 at 11:42:17AM +0100, Matt Sealey wrote:
>> > I have just been told by friend that you can not convert a line from ISDN
>> > to ASDL, is this true?
>>
>> Well ADSL works on the basis of funny tricks it can do by sending data down
>> an 'analogue' copper wire under your road. Just like 56k modems, if you start
>> putting in more than one analogue-digital step on route, the data gets
>> smashed.
>>
>> ISDN is a purely digital line, hence that's one step. Your data won't even
>> get out of the house.
>>
>> That's the SIMPLE version, anyway ;)
>
> But the ISDN is still carried by thin pieces of copper wire - the same as
> the analogue line... same cable - different pair!
>
> All they do, is put "extra" equipment at each end of the pairs of cable to
> determine it's usage - analogue, ISDN or ADSL...
I was under the impression that the kit they put at YOUR end of the line
(or is it at the exchange?) for ISDN was mutually exclusive to ADSL because
it put the data out in funny, condusive-to-ISDN-transfer methods.
Hence, modulating it to ADSL type carrying, and then having some freak
ISDN box mess with it wouldn't be a good idea, as it kills the tricks (the
same ones that makes ADSL distance-sensitive, for instance..) that make
it work.
>> subsidising the damn things. Imagine how much you lose on the conversion,
>> and then think of how much of it BT is paying for out of goodwill ;)
>
> Indeed. There is no tecnical reason for doing it - it is purely cost driven
> by BT that is preventing people from changing ISDN->ADSL...
>
> Saying that - BT are trialing ISDN->ADSL conversions atm....
At great cost, I suspect ;)
That said, given the limits on bandwith use, nominal contention ratios for
home use, cost involved for ADSL at this time, and many other factors,
only an idiot would go with ADSL when ISDN would be a darn sight faster
for normal use. A guaranteed 128Kbps link to your free ISP when using
both lines, or a measly 256Kbps-shared-between-the-other-20-in-your
-village-for-twice-the-cost? Which would YOU choose? :)
Thanks
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