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From: kleef@cs.vu.nl (Patrick van Kleef)
Newsgroups: comp.misc
Subject: PhonePhreaking in Europe
Message-ID: <1104@ark.cs.vu.nl>
Date: Tue, 1-Sep-87 10:02:13 EDT
Article-I.D.: ark.1104
Posted: Tue Sep  1 10:02:13 1987
Date-Received: Sat, 5-Sep-87 04:00:06 EDT
Organization: V.U. Informatica, Amsterdam, the Netherlands
Lines: 53

[I post this article here, because the moderator of
DCOM.TELECOM seems to be non-present]


Phone Phreaking in Europe
=======================

Recently, the Dutch monthly Personal Computer Magazine published an 
article by me on how to make free phone calls around the world. As it 
turned out, phone phreaking is possible in Europe too. The article caused 
considerable rows all over the country and furiated the Dutch PTT. The 
technique used is the same as was used in the United States.

Although the Dutch telephone system is basically a 'hacker-proof' 
system, the inventors of the free-phone system discovered a couple of 
toll-free telephone numbers that led to a transport company in Denmark. 
And the lines used were CCITT-C4 connections. These type of connections 
are old and 'open' for hacking. On C4 lines, the inter-network tones are 
distributed over the same telephone line as the caller uses. More than 99 
percent of the 'normal' Dutch telephone lines use a C5 type connection, 
whereby all inter-network tones are sent via a separate telephone line, 
so user intervention is not possible.

C4 lines, however allow user intervention. So the 'phone-phreaks' made 
programs that produced network-tones on most of the popular 
homecomputers. They dialed the 06-number (the Dutch equivalent of the 
US 800-numbers) that led to Denmark and used the computer and a 
speaker to put the C4-tones on the telephone line. This way they could 
call any person all over the world.

Shortly after the publication in Personal Computer Magazine and on radio 
and television, the Dutch PTT put an end to this trick, by rerouting the 
Denmark numbers over C5-lines. But another option remained and remains 
open. Telephone calls can now be made through Spain. The entire Spanish 
telephone system is based on the CCITT-C4 protocol. Therefore, by 
calling Spain and using the tone-program, you can call over the world 
again. Phoning isn't free of cost (you're charged a call to Spain, fl. 1,80 
per minute, about $ 0,90) but it's cheaper than calling the US e.g. 
directly.

And ofcourse, telephone calls from within Spain can be made without 
costs at all. This disturbs the Spanish PTT a great deal, because 
modernization of the telephone system there isn't scheduled before 1989. 
Publication of this phenomena (as El Pais did, following the article in the 
Dutch computer magazine) will lead to an abundant use of C4-programs 
on home computers. Thus presenting the Spanish PTT with possibly many 
millions of costs. The PTT there said they knew it was possible, but 
figured that as long as the C4-trick wasn't disclosed, the number of 
people using it would remain small. They calculated the costs at a few 
thousands every year. This will, ofcourse, go up incredibly.

Paul Molenaar
Bitnet: U00212@HASARA5