TELECOM Digest Sun, 6 Feb 94 10:47:00 CST Volume 14 : Issue 64
Inside This Issue: Editor: Patrick A. Townson
Re: ISDN and Caller-ID (Al Varney)
Re: DID Questions (Tom Watson)
Re: Sprint (Dvorak) Modem Offer (Randy Gellens)
Re: More About INTERNET Connections (Lars Poulsen)
Re: Increasing Cordless Range (John Gilbert)
Re: Increasing Cordless Range (Alan Boritz)
Re: Increase Stand-by Time of Mobile Phones (M.A. Karinen)
Re: Increase Stand-by Time of Mobile Phones (Gary Breuckman)
Re: Increase Stand-by Time of Mobile Phones (Bill Mayhew)
Re: Increase Stand-by Time of Mobile Phones (Bill Walker)
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Date: Sat, 5 Feb 94 22:46:30 CST
From:
[email protected]
Subject: Re: ISDN and Caller-ID
Organization: AT&T
In article <
[email protected]>
[email protected] (Ketil
Albertsen,TIH) writes:
> In article <
[email protected]>, Will Martin <wmartin@STL-06SIMA.
> ARMY.MIL> writes:
> .... Our PABX generates a caller ID for outgoing calls, based on
> which of the 300 local lines originates the call. That is a private
> PABX (an NT2, in ISDN terms) which we control 100% ourselves, so it
> cannot generate "network verified" IDs. The telco switch can verify
> that the user supplied ID is one of the 300 subscriber numbers
> assigned to that PRI, but not which one of them. I don't know if it
> marks the ID as "network verified" when it *might* be the right one --
> I would guess that the telco is responsible for identifying the
> *subscriber* (which is our college), and so confirm the ID.
Bellcore's thoughts on this are embodied in TR-268, which goes
beyond the ITU Q.93X procedures (and is very World-Zone-1 specific).
In summary:
1) If the calling user equipment (PRA/PRI or BRA/BRI line) is required
to supply the Calling Party Number (CPN) on all originations, then
the call is rejected if the CPN is not supplied or one of the valid
DNs associated with the equipment. If valid, the supplied number
is used for billing, determining any per-DN call characteristics
such as permitted Bearer Capabilities and presubscribed IXC/INC and
this number is supplied to the terminating switch as the CPN.
Any received CPN by the called party will be marked "user-provided
number, number passed network screening".
2) If the line is not required to supply a CPN, and doesn't, a default
DN associated with this line and Bearer Capability is used for
billing, per-DN characteristics and CPN to the far switch.
I believe the CPN, if delivered to the called party, will be
marked "network-provided number".
3) If the line is not required to supply a CPN, but does, and the
line is marked CPN SCREENING=NO, the default DN (above) is used
for billing and per-DN characteristics. The unscreened CPN and
the default DN are passed to the terminating switch. The default
DN is used for call trace, etc. purposes and may also be delivered
to the called party. The CPN, if delivered to the called party,
will be marked "user-provided number, number not screened"
4) If the line is not required to supply a CPN, but does, and the line
is marked CPN SCREENING=YES, the supplied number is checked against
the list of valid DNs for this line. If valid, it is handled as in
case 1) above. If invalid, it is handled as in case 3) above, except
the CPN will be marked "user-provided number, number failed network
screening".
"Presentation prohibited" or "Presentation allowed" are also
attributes passed to the terminating user -- if "prohibited" then the
number itself is not delivered (but the "screening" information is
delivered).
As an exercise for the user, try determining how the above applies
to X.25 packet connections. In particular, determine how "screening"
information is delivered, whether a CPN used to set up a Packet
B-channel connection is ever involved in an X.25 connection and how
these procedures interact with Reverse Charging.
> After all, even on a one-subscriber-number BRI, there may be
> eight phones and the switch cannot distinguish between them -- the PABX
> is just a scaled-up version of that situation.
A better PABX analogy might be a ten-number BRI with eight phones
and two B-channels, and multiple DN apperances on each of the eight
phones.
Al Varney
------------------------------
From:
[email protected] (Tom Watson)
Subject: Re: DID Questions
Date: Sat, 05 Feb 1994 18:52:26 -0800
Organization: Apple Computer (more or less)
In TELECOM Digest, V14 #53, Thomas Tengdin <
[email protected]> asks:
> Can anyone tell me how DID lines pass the number down the trunk?
Previous follow ups to this question related the techniques that are
used for DID service. Having been on the ordering side of these
goodies (we used them in answering service computer boxes) I note some
other facts relating to DID service.
1) If you want to "crudely" simulate the CO side of DID service, a regular
dial phone (if you get pulse type signalling) works very well. A bi-color
LED in series will also tell you the status of answer/wink supervision.
2) If you don't provide battery back to the central office, a whole
bunch of people get upset (telephone company, the DID user, and the
guy calling in). Sometimes it takes frantic calls to repair droids to
re-activate the trunks. Usually the calls require such items as T&N
numbers, trunk group numbers, or other such data that you never have
in front of you, and is usually NOT supplied by the telephone company.
3) Crossbar (#5XB) behaves much differently from ESS1/1A offices. On
Crossbar offices there is no timeout (or at least it is really wierd)
when the customer site has no battery. You end up sticking a "sender"
which the CO guys get really upset about. On ESS offices the dial
pulses (the only type of signalling I had experience with) are not
done by opening & closing of a contact, but rather by the CO changing
battery voltages on its side of the line. In addition, the first
pulse of a dialed digit has a "serration" in it. This serration
usually won't effect relays as it is very fast, but if you detect loop
signalling by an optical isolator (like we did) its there!!
4) The T1 carrier facilities used to transport DID trunks are called
DPO (dial pulse originate) and DPT (dial pulse terminate). Some of
these draw small amounts of current from your equipment when idle.
Don't make your loop sensor too sensitive, as it will be tripped up
all the time.
5) The customer equipment determines when the call is "answered" by
reversing the polarity of the loop supply. When telephone companies
supplied termination equipment, the audio path was one way (from PBX
to CO) until the call was "answered" to prevent people from not
answering calls and getting work done. This allowed the PBX to send
back things like ring, busy, and announcements. You could also
"cheat" and not send back answer supervision. This is frowned upon,
as the call is free. At one time I had a tone & voice pager that was
connected to DID trunks that didn't return answer supervision. I
could page from pay phones and get my money back. Fun and games (they
don't do it any more).
6) The number of digits pulsed (or signalled) out from the CO is
variable; we usually used three digits (the last three of the phone
number), even though we didn't subscribe to 1000 phone numbers.
7) The billing arrangements are in two parts: Number of trunks, and
the number of numbers. The number groups can be diverse, I've seen
xxx-3400 to xxx-3499 and xxx-5600 to xxx-5699 on the same trun group
signalling 400-499 and 600-699.
I hope this aids in the understanding of DID lines and how they work.
Have fun!
Tom Watson
[email protected]
------------------------------
From:
[email protected]
Date: 06 Feb 1994 00:30:00 GMT
Subject: Re: Sprint (Dvorak) Modem Offer
Earlier, I wrote:
> Finally, I talked to a supervisor, and we went through the notes on my
> account. It seems my original call was taken by someone not familiar
> with the offer, and this person failed to sign me up for the modem
> (but did switch my line).
> When I pointed out that I had called to sign up for the modem before
> the offer expired, and that it was no fault of mine if the Sprint rep
> didn't do it right, the supervisor promised to contact the manager in
> charge (no longer Diane Worthy, it seems) and appeal. This was at the
> end of last year, and I still have not heard anything.
I received a call back from the supervisor, and he told me a modem would
be shipped.
Randall Gellens
[email protected]
A Series System Software
Unisys Corporation [Please forward bounce messages
Mission Viejo, CA to:
[email protected]]
------------------------------
Date: Sat, 5 Feb 94 23:04:22 +0100
From:
[email protected] (Lars Poulsen)
Subject: More About INTERNET Connections
After my article about Internet conenctions, I have received many
generic questions about connecting to the Internet. Here are some answers:
1) I have a BBS (or I'm setting one up). How do I get Internet Email
access?
The least expensive way to get mail to and from the Internet from
a BBS environment is by using the UUCP protocol to connect to
a site that has a "real" Internet connection. The Waffle BBS system
(which is shareware) uses UUCP for external mail, and can also
link up with USENET newsgroups [foot note 1].
If you aren't on friendly terms with an Internet site that can
be persuaded to give you dial-up UUCP access, call UUNET or PSI.
2) The article listed several classes of Internet service providers in
the US. How do I get service in Europe?
The same classes of service exist in Europe. Be prepared to spend more
for the telephone call charges, though. Except for Austria, there are
no untimed local calls in Europe, so far as I know.
There are several providers. EUNET has outlets in most west European
countries. They can be reached by sending mail to
[email protected] and
asking for rates and local access sites.
3) You mentioned a PC or Mac e-mail client called Eudora. Can you tell me
more?
Eudora exists in a Mac version (which I have used with MacTCP) and in a
PC/Windows version. It used to be NCSA freeware, but the author moved to
QualComm who have decided to take it commercial. The older version is
still available by FTP from ftp.qualcomm.com.
In a TCP environment, Eudora uses Post Office Protocol (POP3) to
receive mail, and uses SMTP to send mail. Mail folders live on your PC
(or Mac) in Unix mail file format. Your mailbox lives on a Unix host
with a POP3 server daemon.
When you start Eudora, and at interval thereafter, it polls the POP
server, which authenticates you (username/password) and then hands over
the current contents of /usr/spool/mail/username, which is then
appended to the tail end of your INBOX. The interface then looks a lot
like MAILTOOL. (It also looks a lot like QuickMail.) You can now read,
reply and compose messages all you like. Later, you can flush the
OUTBOX to the SMTP server on the same or a different mailhost.
At least in the Mac environment, you can login in regular async mode
instead of using TCP for uploads and downloads. Using PPP to connect to
the host by modem, would be another option.
The commercial Windows package costs $65 including floppy, manual and
a year of free maintenance. The manual alone is $15.
For more information, send mail to
[email protected]
4) You mentioned the PDIAL list of public access systems.
How do I get this list?
Send a message with the phrase "send PDIAL" to
[email protected].
Lars Poulsen Internet E-mail:
[email protected]
CMC Network Products Phone: (011-) +45-31 49 81 08
Hvidovre Strandvej 72 B Telefax: +45-31 49 83 08
DK-2650 Hvidovre, DENMARK Internets: designed and built while you wait
------------------------------
From:
[email protected] (John Gilbert)
Subject: Re: Increasing Cordless Range
Organization: Motorola, LMPS
Date: Sat, 05 Feb 1994 12:43:52 -0600
In article <
[email protected]>,
[email protected] (Bill
Leeke) wrote:
> I would like to increase the range of my cordless phone. Does anyone
> know if there is an easy way to do this? i.e. clip/screw a few
> resistors ...
> Would it be possible to put a linear amp on the base? Could you also
> increase the gain of the base antenna?
If you live in an area with lots of neighbors, the quickest and
easiest way to increase your range is to buy a 900 MHz phone and put
the base as high as possible in your house.
An external antenna could be put on the base of a 46/49 phone, but
this would violate the FCC part 15 type acceptance of the phone.
Additionally, your base would receive more interference from other
handsets so you would have fewer clear channels available for your
use. You would also have a much higher probability of causing
interference to your neighbors phones and baby monitors. In an area
with very light use of the 46/49 band, an external antenna might help.
RF amplifiers at the base and handset probably wouldn't help without
other changes to the radios. Other elements of the radio such as the
duplexers and RF bypassing aren't designed for the higher power and
probably wouldn't work as well as before.
Linear amplifiers aren't required for FM signals and consume more
battery than a class C (non-linear) amplifier.
John Gilbert
[email protected]
------------------------------
Subject: Re: Increasing Cordless Range
From:
[email protected] (Alan Boritz)
Date: Sun, 06 Feb 94 07:41:31 EST
Organization: Harry's Place BBS - Mahwah NJ - +1 201 934 0861
[email protected] (Bill Leeke) writes:
> I would like to increase the range of my cordless phone. Does anyone
> know if there is an easy way to do this? i.e. clip/screw a few
> resistors ...
> [TELECOM Digest Editor's Note: Remember that whatever you do, you also
> need to increase th handset's range accordingly.
Remember also that it's highly illegal to do that in the US.
aboritz%
[email protected] or uunet!drharry!aboritz
Harry's Place BBS (drharry.UUCP) - Mahwah NJ USA - +1-201-934-0861
[TELECOM Digest Editor's Note: Yes indeed, it is illegal, and although I
don't know of any cases where the FBI/FCC/whoever has made a case out of
it, the fact is to increase the range of a cordless phone is a lot of
work for little improvement, a lot more interference, and the frustrations
of the handset (at some newsly created distance away) being able to
receive the base quite clearly but not being able to get back to it. Ever
get in the outer fringes of where your cordless phone will operate and
have an incoming call arrive? Your handset chirps as it should, you press
the appropriate key to answer but the handset keeps on chirping. Why?
It hears the base calling it, but the base hears nothing back in return
and keeps on sending a ringing signal. It is *hard* to increase the range
of the handset, thus the equal distance in either direction which must be
maintained for the unit to work properly is lost. In fact, increasing the
base output is *so easy* (just a trim pot or two, clip a diode maybe) and
*it* (the base) will talk loud and far. But for what reason if the handset
cannot get back to it and all the baby monitors in between get to listen
to it instead. Overall, don't bother. Go 900 megs with the base unit as
high as you can get it. PAT]
------------------------------
Date: 06 Feb 94 03:55:51 EST
From: M A Karinen <
[email protected]>
Subject: Re: Increase Stand-by Time of Mobile Phones
It seems to me that the problem described in a recent message:
> It is a bit of pain to carry a heavy battery and to re-charge it
> everyday. Most of the battery power is consumed during the stand-by
> time. People can't afford to talk to long.
... should mostly be history by now, if you have an advanced cellular
network and a modern handheld phone.
My analogue Nokia 101 handset, a very small one, easily stays powered
for about four days (4*24 hours) with light calling with the thicker
battery, and two days (2*24 hours) with the smallest battery. The
thicker battery provides about two hours of talk time in city environs
(ie the phone probably uses low power because the cell site is
nearby); the smallest battery does about 45-50 minutes. The thick
battery carries me well through two business days of active calling,
typically, and the thin one through one day. On my previous phone the
power ran out halfway through the day: I understand the improvement
come through something called "battery save managament" that was
installed in the cellular network (the NMT system), and new phones
compatible with the feature. I do not know how the battery management
feature works, in practice.
So, I am fairly happy -- if I did not need to worry what my typical 45
minutes of daily airtime costs ...
------------------------------
Date: Sun, 6 Feb 1994 07:04:08 -0800
From:
[email protected] (Gary Breuckman)
Subject: Re: Increase Stand-by Time of Mobile Phones
In article <
[email protected]> is written:
> I am a new mobile phone user. In general, it is an useful toy.
> However, it also has some potential problems. The biggest problem is
> with the battery life. It is a bit of pain to carry a heavy battery
> and to re-charge it everyday. Most of the battery power is consumed
> during the stand-by time. People can't afford to talk to long.
> The problem could be solved if the mobile phones are designed
> differently. For instance, it could have an internal switch which
> turned the receiver circuit on and off periodically for a short interval
> to monitor the incoming calls. Off because it should be on during the
> conversation. For instance, turn it on for 0.01 seconds every second
> would not miss an incoming call but could increase the stand-by time
> by a factor of 100. We all know that a pager consumes very little power
> and many cordless phones do this to save battery power.
Since the same folks who make pagers make cellular phones, I would
think that at least some of the power conservation schemes have been
implemented, and that they are doing the best job they can.
What I think is a better idea is to use a pager, with voicemail if
desired, and have folks call that. You can then choose which calls to
return using your expensive cellular airtime, and if a landline phone
is available, you can return calls using that. You would turn your
cellular off entirely except when making calls.
[email protected]
------------------------------
From:
[email protected] (Bill Mayhew)
Subject: Re: Increase Stand-by Time of Mobile Phones
Organization: Northeastern Ohio Universities College of Medicine
Date: Sat, 05 Feb 1994 21:16:04 GMT
I am pretty sure that pocket type cellular phones here in the US use a
power saving feature that cycles the reciever off and on while the
unit is in standby mode. It seems to take a second or two for my
Motorola pocket phone to decide it should ring. The cellular paging
channel does send the page out to the mobile several times in a row,
so there is a reasonable chance of catching the page even if the
mobile unit were to cycle its receiver. The Motorola flip phone will
run for more than 24 hours in standby mode with a nickle-metal-hydride
battery. The unit and battery are easily small enough to fit inside a
suit coat pocket. The 24 hour ni-cd battery is a bit bigger than the
n-m-h pack, but has the advantage of tolerating overcharging better
and has less self-discharge when not in use.
I'm not familiar with the way GSM phones in other parts of the world
work, so there might be a reason they need to stay on continuously.
Bill Mayhew NEOUCOM Computer Services Department
Rootstown, OH 44272-9995 USA phone: 216-325-2511
[email protected] amateur radio 146.58: N8WED
------------------------------
From:
[email protected] (Bill Walker)
Subject: Re: Increase Stand-by Time of Mobile Phones
Date: Sat, 05 Feb 1994 16:00:26 -0800
Organization: Qualcomm, Inc.
In article <
[email protected]>,
[email protected] (Yang
Yu-shuang) wrote:
> Hi Net Friends,
[cellular phone battery life is too short]
> The problem could be solved if the mobile phones are designed
> differently. For instance, it could have an internal switch which
> turned the receiver circuit on and off periodically for a short interval
> to monitor the incoming calls. Off because it should be on during the
> conversation. For instance, turn it on for 0.01 seconds every second
> would not miss an incoming call but could increase the stand-by time
> by a factor of 100. We all know that a pager consumes very little power
> and many cordless phones do this to save battery power.
Unfortunately, you _would_ miss an incoming call, since in a cellular
network the call is really just a short message (a "page") sent to
your phone. Unless the base station knows exactly when the mobile
will "wake up", calls cannot go through.
The U.S. CDMA Digital Cellular system (as specified by EIA/TIA IS-95)
provides for a scheme such as you describe. The Paging Channel is
divided into time slots, and mobiles may be set up to only wake up
during certain slots. When the mobile registers in the system, it
informs the system in which slots messages can be sent to the mobile.
I note that your address is in Australia, which I believe is currently
deploying GSM. I don't know whether GSM provides for this.
Bill Walker -
[email protected] - QUALCOMM, Inc., San Diego, CA USA
------------------------------
End of TELECOM Digest V14 #64
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