From: Arthur@cswamp.apana.org.au (Arthur Marsh)
Newsgroups: comp.dcom.isdn
Distribution: world
Subject: ISDN international tariffs
Date: Sun, 27 Dec 1992 09:46:26 +1000

On Sat 19 Dec at 21:45 Al Varney wrote:

 AV> From: varney@cbnewsd.cb.att.com (Al Varney)
 AV> @Message-ID: <1992Dec19.214534.3982@cbnewsd.cb.att.com>
 AV> @References: <724643806.AA00663@cswamp.apana.org.au>

>With a good modem, one can get about 1500 cps on one of these
64
>kbps PCM voice circuits.

 AV>    1500 cps in one direction...

Well, V.32bis is supposed to be full duplex, but I haven't had
too much luck with protocols that transfer files in both
directions at the same time. Under good conditions with
V.32bis/MNP 4 I've had 1700 cps one way on non-compressible data,
but not on international calls.

>With one 64 kbps ISDN B channel, presumably 7500 cps throughput
is possible, a 
>five-fold increase at nearly 3 times the per-minute cost plus a
big flagfall.

 AV>    Where is 7500 cps from???  

a wild guess (-:, comparing traffic in a single direction for
both systems.

 AV> Sounds like a good trade-off, if you have enough 
 AV> data to off-set the "flagfall". If not, you're only 
 AV> talking about A$1 or two per call....

Australian dollars are called South Pacific Pesos after all (A$1
roughly = US $0.69). There is also a certain irony in the fast
call setup time of ISDN having such a high price. Non-local voice
calls here now have a 12 cent flagfall.

>Are there other costs to the telephone company involved that
>already has ISDN capable equipment that can in any way justify
>the extra cost of ISDN?

 AV>    Switches have to recognize and route properly requests 
 AV> for 64 kbps data service.  In the USA, even 56 kbps 
 AV> requires either dedicated MF trunks or SS7 signaling 
 AV> between switches.  Data users may also require better 
 AV> performance (lower bit error rate) and more maintenance 
 AV> attention on the facilities.  The labor and switch 
 AV> updates/replacements are not cheap.  The ability to 
 AV> switch echo suppressors in and out over shared 
 AV> facilities could also be a cost, as could any 
 AV> requirement to route 64 kbps data calls over land 
 AV> facilities only (no satellite).

Echo suppressors should be switched off by the initial 2100 Hz
answer tone of fax machines and CCITT compliant voiceband modems.
The other points raised were significant, but could easily lead
to a "my country's telephone companies' equipment is more CCITT
compliant and more modern/reliable/etc than yours" type argument
that we'd all like to avoid.

 AV>    And last, are you sure your modem call is allocated the 
 AV> full PCM channel?  Many overseas calls use forms of 
 AV> multiplexing that share N channels with N+m calls.  
 AV> Multiplexing/compressing raw data is not an option for 
 AV> 64 kbps data calls (in my opinion).

Usually (and for calls to New Zealand, always). I have received
information from AOTC's Technical Directorate, after raising my
problems with the chairman of Austel, Australia's
telecommunications regulator.

 AV> Al Varney  -- my employer owns a telecom service, but I
don't work for 
 AV> that part of AT&T, nor do I speak for ANY part of AT&T.

Others joke about how many people AOTC can employ with the phone
bills I pay.

AOTC (Australian and Overseas Telecommunications Commission) =
old Telecom Australia + old OTC (Overseas Telecommunications
Commission).

AOTC is also known as America's Other Telephone Company due to
having a US citizen, Frank Blount, ex AT&T, as boss. OTC is also
known as Optus Training College due to the numbers of former OTC
employees who left to work for Optus, Australia's second
telecommunications carrier.

 * Origin: Camelot Swamp MJCNA, Hawthorndene, Sth Australia
(8:7000/8)