On Fri 15 Mar at 23:36 Poe Lim (3:623/630) wrote to Arthur Marsh:

 AM> lasts. Some of the 326X series have synchronous 
 AM> operation and synchronous data compression which low end 
 AM> modems lack and niche

 PL> How does sync data compression work?

I haven't figured it out from Motorola's papers on the subject.

 AM> For the best possible V.34 operation between a site 
 AM> with ISDN and a remote site without ISDN, the ISDN 
 AM> equipped site should have a 4 wire interface to its V.34 
 AM> modem (either internally as Ascend presumably does, or 
 AM> by having a 4 wire interface on the ISDN terminal adapter).

 PL> Is there any reason for 4 wire? Does ISDN require 4 wire? 

"4 wire" in this means using separate channels for voice freqency
signals in different directions. This would remove the problems of
separating out the voice frequency signals in the modem.

Physically, Basic Rate ISDN uses 2 wires from the exchange to the NT1, then
a larger number of wires (varying depending on whether there is a power
rail) on the S-Bus.

 AM> Four wire analogue operation may also be easier to 
 AM> provide than ISDN for remote sites that do need high 
 AM> speed data operation beyond 7 km from the nearest 
 AM> exchange/RIM/RCM/...

 PL> So I gathered, unless there is a booster.

Which Telstra still charge you an arm and a leg for...

--- msgedsq 2.1