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Re: (ASCEND) Dialing to Denmark from Canada requires 56KR ?
Recently I (Larry Williamson <larry@mitra.com>) wrote:
> We have a small branch office in Denmark. I have had no luck
> connecting our 1800 to their p50 except using 56KR.
Matt Holdrege <matt@ascend.com> wrote:
>
> Who is the carrier(s)? Do they have CCS signalling to Denmark? You need to
> arrange for a clear channel 64 connection which should give you fast setup.
I only know for sure that Bell Canada's ISDN is served by Stentor. I
have no idea what type of equipment is used either here, or in
Denmark. I do know that I get 64K for local calls. This is the only
long distance setup I have had to deal with so far.
The following item offers some insight. If all this is true, I am
very disappointed.
John_Marks@ascend.com wrote:
>
> You may already know this part. In North America the phone system is much
> older than most of the rest of the world. In order to pass signalling
> information over the link at the same time as data and voice, the
> Robbed-Bit Signalling technique was developed. Remember each of the
> channels on a T1 is just an eight bit slice of the entire signal.
> Robbed-Bit Signalling essentially stole a bit from each of channels in
> which to insert one bit of signalling info; after receiving a number of
> channels a signalling word would be put together. Because seven bits are
> used for data and one for signalling the best we could get out of it was 56
> Kbps. In Europe after the War, they decided to replace older equipment with
> new "out-of-band" signalling systems, hence the E1. This new system used
> one of the channels for all of the signalling and left the remainder to
> operates at full eight bits per channel or 64 Kbps (They also increased the
> number of channels to 32 of which 30 where for data/voice use). This lent
> itself to our PRI type circuits. Ok, what has this to do with a call from
> Canada to Denmark.
>
> To maintain 64 K through-out the North American telephone system for PRI's
> we had upgrade many of the trunks to an "out of band" signalling technique.
> The problem is all the legacy equipement and software that is geared toward
> 56K, Robbed-Bit. We developed Signalling Systems 7 or SS7, this puts a
> parrallel system just for carrying the signals. Although, this the least
> expensive option, it is a substantial "upgrade" cost, so major centres get
> done first and then connections between cities within each telco's serving
> area. Next, the various telco's then assign agreemnts to pass SS7
> information between themselves and lastly, the older international trunks.
> It was just year and half ago that you could not get 64 K between Toronto
> and Vancouver. You still can't get 64 K to all the U.S., carriers from Bell
> Canada or the other Stentor members.
>
> Why the 56 KR designation, I am not 100% sure. The difference between the
> 56K setting and the 56KR setting is that the 56KR stands for "Restricted"
> and enforces the 1's density of the channel. The 56KR setting is generally
> used with AT&T manufcatured switches. Most likely this is what they have in
> Denmark to tie into the North American trunks, or you are going through a
> U.S. carrier at some point and they have an AT&T switch (If you orginate
> inside Canada it won't go to the U.S -- CRTC rules and all).
>
> I can't explain the long set-up time, but your assumption is probably
> right. As for ping times, again the propegation delay created by the
> distance will be the major factor. I am not sure where you are based but,
> the data must travel from your sight through a bunch of curcuits and
> perhaps carriers, then to the Transalantic carrier, over the Alantic,
> probably to Britian. From there is must work its way to Denmark, ( from
> Denmark to Greenland if that is the case). Who knows how many kilometers of
> wire it is going through. A general rule of thumb to get the propegation
> delay, is take the number of kilometers of wire/fibre, divided by the speed
> of light. For a ping since it is a round trip double this number. This
> value of course will be faster than the actual, but it should give you a
> feel for the delay due to distance.
>
> I hope this helps
>
> John Marks
> Sr. Systems Engineer
> Ascend Canada Inc.
>
>
> >From: Larry Williamson <larry@mitra.com>
> >Date: Sun, 23 Nov 1997 23:42:14 -0500
> >Subject: (ASCEND) Dialing to Denmark from Canada requires 56KR ?
> >We have a small branch office in Denmark. I have had no luck
> >connecting our 1800 to their p50 except using 56KR.
> >Is this to be expected?
> >A couple of other things too...
> >Ping times seem to be quite long. I guess this makes some sense given
> >the distance between us. Typical ping times are in the 160ms range.
> >Call setup takes about 11 seconds. Again, given the distance, I guess
> >this is reasonable.
> >Larry
>
>
>
>
>
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