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) TELECOM Digest is an electronic journal devoted mostly but not exclusively to telecommunications topics. It is circulated anywhere there is email, in addition to various telecom forums on a variety of public service systems and networks including Compuserve and GEnie. Subscriptions are available at no charge to qualified organizations and individual readers. Write and tell us how you qualify: * telecom-request@eecs.nwu.edu * The Digest is compilation-copyrighted by Patrick Townson Associates of Skokie, Illinois USA. We provide telecom consultation services and long distance resale services including calling cards and 800 numbers. To reach us: Post Office Box 1570, Chicago, IL 60690 or by phone at 708-329-0571 and fax at 708-329-0572. Email: ptownson@townson.com. ** Article submission address only: telecom@eecs.nwu.edu ** Our archives are located at lcs.mit.edu and are available by using anonymous ftp. The archives can also be accessed using our email information service. For a copy of a helpful file explaining how to use the information service, just ask. TELECOM Digest is gatewayed to Usenet where it appears as the moderated newsgroup comp.dcom.telecom. It has no connection with the unmoderated Usenet newsgroup comp.dcom.telecom.tech whose mailing list "Telecom-Tech Digest" shares archives resources at lcs.mit.edu for the convenience of users. Please *DO NOT* cross post articles between the groups. All opinions expressed herein are deemed to be those of the author. Any organizations listed are for identification purposes only and messages should not be considered any official expression by the organization. ---------------------------------------------------------------------- Date: Sat, 5 Feb 94 22:46:30 CST From: varney@ihlpe.att.com Subject: Re: ISDN and Caller-ID Organization: AT&T In article ketil@edb.tih.no (Ketil Albertsen,TIH) writes: > In article , Will Martin 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: tsw@cypher.apple.com (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 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 tsw@cypher.apple.com ------------------------------ From: RANDY@MPA15AB.mv-oc.Unisys.COM 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 randy@mv-oc.unisys.com A Series System Software Unisys Corporation [Please forward bounce messages Mission Viejo, CA to: rgellens@mcimail.com] ------------------------------ Date: Sat, 5 Feb 94 23:04:22 +0100 From: lars@eskimo.CPH.CMC.COM (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 info@eu.net 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 jwn2@qualcomm.com 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 info-deli-server@netcom.com. Lars Poulsen Internet E-mail: lars@CMC.COM 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: johng@ecs.comm.mot.com (John Gilbert) Subject: Re: Increasing Cordless Range Organization: Motorola, LMPS Date: Sat, 05 Feb 1994 12:43:52 -0600 In article , bailey@casbah.acns.nwu.edu (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 johng@ecs.comm.mot.com ------------------------------ Subject: Re: Increasing Cordless Range From: drharry!aboritz@uunet.UU.NET (Alan Boritz) Date: Sun, 06 Feb 94 07:41:31 EST Organization: Harry's Place BBS - Mahwah NJ - +1 201 934 0861 bailey@casbah.acns.nwu.edu (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%drharry@uunet.uu.net 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 <73270.2240@CompuServe.COM> 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: puma@netcom.com (Gary Breuckman) Subject: Re: Increase Stand-by Time of Mobile Phones In article 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. puma@netcom.com ------------------------------ From: wtm@uhura.neoucom.EDU (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 wtm@uhura.neoucom.edu amateur radio 146.58: N8WED ------------------------------ From: wwalker@qualcomm.com (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 , yang@mundoe.maths.mu.OZ.AU (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 - WWalker@qualcomm.com - QUALCOMM, Inc., San Diego, CA USA ------------------------------ End of TELECOM Digest V14 #64 ***************************** ------------------------------------------------------------------------------- Downloaded From P-80 International Information Systems 304-744-2253