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From: DREUBEN@eagle.wesleyan.edu (Douglas Scott Reuben)
Newsgroups: comp.dcom.telecom
Subject: Re: Answer Supervision on Cellular Roam Ports
Message-ID: <15963@accuvax.nwu.edu>
Date: 12 Jan 91 05:08:16 GMT
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X-Telecom-Digest: Volume 11, Issue 24, Message 1 of 9


Hi-

In article <15877@accuvax.nwu.edu>, forrette@cory.berkeley.edu (Steve
Forrette) writes:

When roaming in a foreign system:

> ...[S]omeone has to dial into the roamer port, then
> enter my 10 digit number to reach me.  The problem is that if they are
> calling long distance, they must pay a toll charge for each attempt,
> whether or not I'm on the air, since the call supervises at the point
> the secondary dialtone is provided.

> Since cellular is provided through DID or some other method whereby
> the cellular switch appears as the "end office," why can't the
> supervision be done based on when the call is actually answered?  

I'm by no means an expert on DID, but I can tell you that there WERE
many ports that did NOT return supervision, although few, if any,
remain.

For example, Cell One/San Francisco, until maybe mid-July this summer
(1990) did NOT return supervision until the called mobile party
answered. When they changed this, I called them to find out why, and
they told me: "Oh, so customers can press the "#" button down if they
make a mistake when dialing in the number. Otherwise, when you call
with a Calling Card, you will be disconnected." Quite true, but I
don't think this is the reason.

I recall discussion on the Digest about this in perhaps late-1987 to
early-1988. From what I gathered, AT&T used to allow this sort of
signalling to go through. IE, the talk path would be open BOTH ways,
even before supervision was returned. Thus, a caller calling a roam
port (or anything else, like an automated PBX attendant which accepted
Touch Tones), would hear the dial tone, AND be able to Touch Tone in
the desired mobile number.  When the mobile answered, supervision was
returned, a billing for the call commenced. If the mobile was
unavailable, then no supervision would be returned, and the caller
would not be billed for the call to the roam port.

However, according to the postings (and this is quite hazy, so please
DO correct me here), AT&T installed a new system in their 4ESS(?)
toll-switches, which didn't allow for the CALLED party (ie, the roam
port) to hear the calling party (ie, the person entering the touch
tones) UNTIL supervision was returned.  That is so say, TWO-way
conversations commenced AFTER supervision, not before, as had been the
case. You could still hear the party you were calling, but they
couldn't hear you until their end sent out a supervision "wink" (or
whatever).  I don't recall any stated outstanding reason for this,
although a few were presented.

Some mobile systems didn't seem to realize this. For example, Cell
One/South Jersey (New Jersey) used to have non-supervising ports at
201-715-7626 and I think the other was 609-575-7626. In the Spring on
1990, they changed the numbers (why I don't know), to 908-610-7626.
This new 908 port worked the same way the old ones did, ie, did not
return supervision UNTIL the called party actually answered. Yet for
some reason, the new port worked under the "new" AT&T "rules" (no
callING to callED party conversation until supervision), so if you
called via AT&T, you COULD NOT ENTER *ANY* TONES!

Callers in New Jersey for the most part were fine, as NJ Bell doesn't
seem to care about supervision. Also, callers over MCI and Sprint
didn't notice this, either, as they appear to work differently than
AT&T. It was VERY difficult to convince Cell One/South Jersey that *I*
was correct that their port was "not working", since each time they
called in locally (via NJ Bell, not AT&T) it worked just fine! And
they even had MCI (their LD co, it seems) call them to try it out, and
MCI reported no trouble. I finally had to three-way them to let them
hear what was going on. Eventually, they changed the port to
automatically return supervision.

This sort of spoiled it for non-AT&T customers, ie, those coming in
over NJ Bell or some non-AT&T LD Co. Previously, they could access the
port for free, unless, of course, the mobile was active and answered
the phone. Now, all calls are billed, regardless of an answer. The
Cell One/South Jersey port covers a wide area (DMX), from New York
City's Metro One system, to North Jersey (Metro One), to South
Jersey/Trenton (Cell One), to Atlantic City/Vinland (Cell One), to
Phil (Metrophone) and Wilmington, DE, (again, Cell One.) Thus, the
port was quite useful to me, as I could tell people to call me at ONE
roam port, and I could be reached from all of lower New York all the
way down to about 20 miles north of Baltimore, where the DC system
takes over. Now, since I may very well not be available, I don't want
people to keep trying to and paying for each call, which they wouldn't
have had to do otherwise.

In any event, it seems that such systems are fading quickly as they
are replaced by newer ports that appear to be subjected to the "new"
AT&T supervision rules.

I'd like to hear about any ports that still work the "old" way, and of
course, any corrections on my rather sketchy description of AT&T's
switching system.


Doug

dreuben@eagle.wesleyan.edu  //  dreuben@wesleyan.bitnet