Re: Signal Quality differences in CT1/PRI?

Stephen Fisher (lithium@cia-g.com)
Thu, 28 Aug 1997 15:02:31 -0600 (MDT)

On Thu, 28 Aug 1997, Derric Scott wrote:

> Depends on where your are and your telco, really. Around here it seems
> to practically all be 8 bit within the BellSouth network (guess we do
> get *something* for the high BellSouth (Alabama) rates :). For good
> support of 64k ISDN it is easiest for the telco to have all their trunks
> 8 bit.

The 8th bit is robbed from the data and given to signalling, the only
effect it has on modem data is what Livingston says about 56k in
particular - PRI's will give about 2k more bandwidth on connections on
average than CT1's.

> > I ask because I've been getting pretty lousy connection rates to my
> > PortMaster (CT1, 26400 right now but as low as 21K or 19.2K), and in
> > testing from the same end-user modem to a PortMaster on PRI, get
> > consistent 28.8 connects.
> >
> > I understand that there can be a difference, but that big?

Sounds like a line-side and not trunk-side CT1 to me. I have personally
gotten 46k connections through a CT1 PM3.

For the most part my trunk-side CT1's give pretty good connection rates
(including a lot of 31.2k and some 33.6k even with the old modem cards).

- Steve
- Systems Manager
- Community Internet Access, Inc.
- Gallup and Grants, New Mexico