-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 2012-08-25 04:07, James Knott wrote:
Carlos E. R. wrote:
On the other hand, do you remember those movies where the bad guy makes a phone call to the police and the call has to last less than 20" or he is identified? That's rubbish, you are identified on on the first second, while ringing, at least on countries like Spain.
Actually, it didn't used to be rubbish. I have worked in telecom going back 40 years and at one point early in my career, I actually worked on some of the old step by step relay systems and even learned to trace calls through them. There's no way it could be done in only 20 seconds. Modern, SS7 sytstems are of course quite different. Also, the phone ID can be spoofed. I get plenty of telemarketing calls where that is done. The originating switch or PBX is the one that provides the ID and it can be set to anything. For example, according to my phone's log, I received a call on Aug 10 from 10000000000. That is in no way a valid number, yet it managed to reach my phone. This is via a regular phone company that provides my home phone. Also, a few years ago, I worked on a phone system where the customer insisted there be no caller ID on outgoing calls, as it was for a woman's shelter and they didn't want anyway for someone to track where those women were. I have also set up VoIP PBXs, where someone in one location could call through another location and appear as though they originated at that 2nd location. It's not at all difficult to do with today's equipment, so accepting from the phone company is not quite as secure as you think.
I also have worked on that field, but not that long. My experience is with the 5EEE only. It is precisely due to that work that I became interested in Linux ;-) Legislation in Spain is such that law insists calls are identified because it is needed to know whom to charge the phone call to, across different companies. It started when the government forced the only telco in existence here (Telefónica), in 1997, to accept indirect phone calls routed via another company (you prefix your call with a 3 digit number, and the call is routed via another telco for the long distance part). I too have seen those strange numbers, like 000000, in my terminal, but unfortunately, after I stopped working there, so I don't have inside knowledge on them. I believe they come via internet gateways. I know that with VoIP machines you have a lot of liberty, you can do anything with numbers and names and routings. It is up to you what you do or fake, which also kind of scares me. Of course, the typical is having a company with two or more sites, and routing the call, inside your network, to the POT network from the site closest to the destination, so that the call is charged local charges instead of long distance. - -- Cheers / Saludos, Carlos E. R. (from 12.1 x86_64 "Asparagus" at Telcontar) -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlA4zaAACgkQIvFNjefEBxokjwCgyKIs65/ZmxnW+JgYI4lxkCXh 4j0An1brmrNNKpDT7lSmn2+ffyK6KdYm =o1HK -----END PGP SIGNATURE----- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org