From: atoscano@taronga.com (A Alan Toscano)
Newsgroups: comp.dcom.telecom
Subject: Re: "Secret" Phone Codes
Date: 26 Jan 93 19:29:27 GMT
Reply-To: atoscano@attmail.com
Organization: TELECOM Digest
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 13, Issue 48, Message 1 of 13

In TELECOM Digest Volume 13, Issue 45, ccoprfm@prism.gatech.edu (Monte
Freeman), a reader in the 404 Number Plan Area, writes about his
strange experionces with calls to 404 988-9664, with and without a
prepended 10732- and asks:
 
> Strange results from 404 land. Anyone got any ideas here?
 
It's my understanding that the 732 Carrier Identificaiton Code
facilitates switched access to AT&T's Subscriber Defined Network
Service (SDN) and also its Virtual Telecommunication Network Service
(VTNS).
 
Under SDN/VTNS, each customer designs its own dialing plan, providing
a "virtual private network." Access to SDNs are normally over
dedicated lines, but small branch locations of a corporation might
"PIC" their outgoing lines to 732, (or prefix seven-digit outgoing
calls with 10732 1 700) in order to facilitate switched access to
their SDN/VTN. As the dialing plan of one SDN will likely vary from
that of another, the network must identify the caller, in order to
know which SDN/VTNS dialing plan to use in routing a call. Thus ANI
plays an important role in implementation of SDN and VTNS switched
access.
 
Normally, if you prefix a call with 10732 and are *NOT* an SDN/VTNS
customer, you'll be told "You have reached a private network. You must
be authorized to access this network..." As noted previously in the
Digest, an exception is 10732 1 404 988-9664, which normally recites
ANI information, presumably to assist AT&T in setting up these
networks.
 
(Most AT&T customers' lines are "PIC'd" to 288 and not 732, thus the
need to include the 10732- prefix to override the PIC default.)
 
LEC payphones normally force all "1+" calls to the "288" network
regardless of any 10XXX code dialed (COCOTs generally block "10XXX-1+"
calls altogether) and "10732-0+" calls are treated like "10288-0+"
calls. Therefore, it's not generally possible to reach this ANI
announcement from an LEC payphone. (NYTel payphones are apparently an
exception.) This is no loss to AT&T, however, since payphones aren't
often included in private networks!
 
"1+" calls to 404 988-9664 carried over AT&T's normal "288" network
and over competitors' networks, reportedly ring without answer. Only
if the call is placed "1+" over the "732" network is ANI recited. It
happens that 404-988 is Smyrna, GA - one of the SDN support sites. I
suppose 404 988-9664 rings "open" on a line at AT&T's facilities
there, and has special significance only on the "732" network. I also
expect that AT&T will change this number if it continues to receive
the increasingly frequent mention in the Digest that it has received
lately!
 
Disclaimer: I work for a VTNS customer with dedicated access, and have
limited knowledge of 10732- switched access. Therefore, much of this
is conjecture. I am not an AT&T employee.


A Alan Toscano -- Houston, TX -- <atoscano@attmail.com> -- <attmail!atoscano>