🚀 go-pugleaf

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.