jdc@aplvax.jhuapl.edu (James David Cover) (12/19/89)
The question I have is whether or not anyone knows anything about whether or not one can run a traceback on a phonecall. A friend of mine says that the phone company is now transmitting a "header" with the call that, if one knows the format, could decode it at display the calling number. I would appreciate any information, possible ic's that might do the decoding, theory, specifications, etc. Please reply via e-mail. Thanx. J. David Cover (jdc@aplvax.jhuapl.edu)
sheriffp@spock (Peter Sheriff) (12/21/89)
I worked for the phone company up here in the frozen north for a
while and I never heard anything about a 'header' being transmitted
down the line. There are some wonderfull things that your central
office can do (depending on how new and sophisticated it is) but this
isn't one I know about. I am now working on the development of one of
the latest C.O.s and again, this "feature" is not on the list. If
anyone knows any different please tell me and I will talk to the
designers here and get our system updated.
Peteadams@swbatl.UUCP (4237) (12/21/89)
In article <1732@limey> sheriffp@limey (Peter Sheriff) writes: >isn't one I know about. I am now working on the development of one of >the latest C.O.s and again, this "feature" is not on the list. If >anyone knows any different please tell me and I will talk to the >designers here and get our system updated. I believe the reference is to the out of band info in SS7 (signaling system seven). I don't know of Canadian plans, but SS7 will eventually become widespread in the US, and allow features like automatic number identification, call traceback and screening and other goodies. -- uunet!swbatl!adams or adams@swbatl.swbt.com | Tom Adams: 314-235-7459 BOOKS WANTED: pre-1930 radio, electrical & scientific topics.
andrew@vax1.acs.udel.EDU (Andrew W Hamilton) (12/22/89)
In article <1732@limey> sheriffp@limey (Peter Sheriff) writes: >... >I never heard anything about a 'header' being transmitted >... >I am now working on the development of one of >the latest C.O.s and again, this "feature" is not on the list. If >anyone knows any different please tell me and I will talk to the >designers here and get our system updated. Here in northern Delaware, one feature as stated in the phone book is that you can dial some sequence after you've recieved a call to find out who it was that called you. There is something like a $3.00 charge, and it's not available on some phones. Also, it's definitely relatively new. I don't know anything about how it works, though. Andrew.
sorka@ucscb.UCSC.EDU (Alan Waterman) (12/23/89)
In article <4344@aplcen.apl.jhu.edu> jdc@aplvax.jhuapl.edu (James David Cover) writes: >The question I have is whether or not anyone knows anything about whether or >not one can run a traceback on a phonecall. A friend of mine says that the >phone company is now transmitting a "header" with the call that, if one knows >the format, could decode it at display the calling number. > >I would appreciate any information, possible ic's that might do the decoding, >theory, specifications, etc. Please reply via e-mail. Thanx. > > J. David Cover (jdc@aplvax.jhuapl.edu) I would also like to get info on this subject.
hermann@cpsc.ucalgary.ca (Michael Hermann) (12/23/89)
Here at the University of Calgary, our new (3-4 years) PBX supports
"trace-back", displaying the originating number on phones which have an LCD.
The PBX is an SL100 made by Northern Telecom. The originating number is only
displayed sometimes, indicating that it'll work only if the caller is on a
central office with new equipment. Long distance calls invariably have the
calling number displayed, which I would assume means the long distance
consortium here (Teleglobe Canada) supports "trace-back" as well.
An idea for for those of us who might want to make use of this feature:
How about an answering machine that scans the header, and only lets the
call through if the calling number is on an "accepted" list? 8-) 8-)
| Mike Hermann | hermann@cpsc.ucalgary.ca ..!uunet!ubc-cs!calgary!hermann
_Organized_ religion is like organized crime; it generates huge profits, preys
on people's weaknesses, and is nearly impossible to eradicate.henry@utzoo.uucp (Henry Spencer) (12/29/89)
In article <6693@lindy.Stanford.EDU> sorka@ucscb.UCSC.EDU (Alan Waterman) writes: >>The question I have is whether or not anyone knows anything about whether or >>not one can run a traceback on a phonecall. A friend of mine says that the >>phone company is now transmitting a "header" with the call that, if one knows >>the format, could decode it at display the calling number... > >I would also like to get info on this subject. I replied by mail to the original, since that's what was requested, but I suppose it's worth a brief posting... A service like this is available in some areas. Only some phone switches support it. Generally it costs money to get it; it is *not* supplied free to everyone. (The phone companies are under great pressure to keep the cost of basic telephone service low, which means charging all the traffic will bear for everything else. Services like call forwarding, when available at all, generally cost the phone company nothing to provide, and tone-dialing service is actually *cheaper* for them than rotary dialing... but charging extra for such "luxury" services provides money that can be used to subsidize basic service.) Claims that it's being done everywhere for free appear regularly, but they are myths. If you are interested in such a service, ask your phone company whether it's available and how much it costs. -- 1972: Saturn V #15 flight-ready| Henry Spencer at U of Toronto Zoology 1989: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
dalyb@godzilla.UUCP (Brian Daly) (01/04/90)
In article <6693@lindy.Stanford.EDU>, sorka@ucscb.UCSC.EDU (Alan Waterman) writes: > > In article <4344@aplcen.apl.jhu.edu> jdc@aplvax.jhuapl.edu (James David Cover) writes: > >The question I have is whether or not anyone knows anything about whether or > >not one can run a traceback on a phonecall. A friend of mine says that the > >phone company is now transmitting a "header" with the call that, if one knows > >the format, could decode it at display the calling number. > > > >I would appreciate any information, possible ic's that might do the decoding, > >theory, specifications, etc. Please reply via e-mail. Thanx. > > > > J. David Cover (jdc@aplvax.jhuapl.edu) > > > I would also like to get info on this subject. An answer to your question is yes -- you can run a traceback on a phonecall provided your system is using signalling system #7 and you have the feature for customer originated trace available. The displaying of the calling number is performed with the use of CCITT Signalling System #7. This provides centralized message exchange on common data channels operating at a transmission rate of 64 Kbps. The system can be divided into two parts: the message transfer part (MTP) and the user part (UP). The MTP contains all the requirements necessary to ensure reliable transmission of messages. The User Part is used for a particular service; i.e. telephony. Signalling system #7 is just starting to emerge into the United States telephone network; there is more than upgrading of a central office that needs to be included into the network (for example, there are signalling transfer points that must be installed). Not all areas have started using SS7. There are many features available with the use of SS7; calling number display, automatic callback, customer originated trace are just a sample. These services are provided by the operating company for a subscription fee. The has been many articles in the telephony literature over the past several years describing signalling system #7. Telephony magazine from February 9,1981 has a good introductory article. I also believe IEEE Communications magazine has had articles devoted to SS7, but I don't recall which issue. Research into signalling system #7 will answer your questions. Brian K. Daly AG Communication Systems, Phoenix, Arizona PO Box 52179, Phoenix, Arizona 85072-2179 Phone: (602) 582-7644 The above comments are my own and do not in any way represent AG Communication Systems.
dalyb@godzilla.UUCP (Brian Daly) (01/04/90)
In article <2284@cs-spool.calgary.UUCP>, hermann@cpsc.ucalgary.ca (Michael Hermann) writes: > > An idea for for those of us who might want to make use of this feature: > How about an answering machine that scans the header, and only lets the > call through if the calling number is on an "accepted" list? 8-) 8-) > > > | Mike Hermann | hermann@cpsc.ucalgary.ca ..!uunet!ubc-cs!calgary!hermann > _Organized_ religion is like organized crime; it generates huge profits, preys > on people's weaknesses, and is nearly impossible to eradicate. One of the features that can be provided with signalling system #7 is selective call acceptance and selective call rejection. With these features, you can place specific directory numbers on a screening list, and if that number calls your number, it will either be accepted or rejected depending upon the feature. A rejected call will get a message that you are not accepting any calls, while the accepted call will ring your phone. There are some really nice features in store for the future! Brian K. Daly AG Communication Systems, Phoenix, Arizona The above comments are my own and do not reflect AG Communication Systems.