In message <4079F583.3010200@outblaze.com>, Suresh Ramasubramanian writes:
[4/12/2004 4:49 AM] Steven M. Bellovin :
Naturally, miscreants (to use robt's terminology) try to find ways to make such calls from the U.S. more cheaply. Sometimes, this involves hacking PBXs, other times, it involves subscription fraud, or a variety of other kinds of misbehavior. The responses are similar to those we use on the Internet -- traffic analysis (similar to looking at NetFlow), blacklisting calls to certain countries from, say, pay phones, etc.
There is another class of people who route calls out from the USA to India (or elsewhere) using VOIP, terminate the calls at an unauthorized (that is, not run by a licensed telco) exchange in india, and then route the calls out through the local pstn or mobile network.
Quite a few of the "call $asian_country for cheap" phone cards you find at ethnic grocery stores seem to work on these lines.
The local telco doesn't see a red cent of any settlement charges when this happens. Local telcos are, of course, all against this, and use any and every excuse to get these exchanges busted - a procedure that typically involves having the local police raid the exchange.
Yes. Depending on the countries and telcos involved, this is either illegal or "irregular" network access. Other schemes involve call-back (with the Internet as the signaling channel -- I first heard of that being used in 1994, when most people outside our business had never heard of the Internet) or calling through a third country if the difference in rates makes that profitable. --Steve Bellovin, http://www.research.att.com/~smb