_________ SWAT MAGAZINE ISSUE FIFTEEN: MARCH 1999 __________ / \___________________________________________/ \ / CLID Faking \ / By =The-Doh-Boy= \ ----------------------------------------------------------------------- OK, in this article I'm going to cover the basics of CLID (Calling Line IDentification) and how it affects the humble phreak. CLID Is Different From ANI!!! A lot of people get confused about the difference between these. ANI is an age old ID method whih is only accessible by your local exchange. Its basically a test of voltage levels in your local loop to see "who's making a call right now" As you can see, anyone outside your exchange has to "trace" the path of the call through a maze of trunk lines. For the local exchange, the loops are grouped into "pools" of certain numbers. So say your number was 123456, well for a start your lucky to have such a memorable number!, but how does the exchange work out your number. Well the main "pool" you are a part of is the 1 pool. This consists of all numbers beginning with 1 in the exchange. This then splits off to other sub-pools, like 10, 11, 12. So after going through six sub-pools your unique number is reached. This is how 175 works for reading out your number (on System X) So if you dial 141 then 175 it will have no effect. CLID is digital information (derived from ANI intially) which is sent from exchange to exchange, and occasionally on to subscribers with the CLID service. This can be withheld by dialling 141 in the UK, or by using star services in the US. 17070 works using this. How can I stop ANI going out on normal calls? Well the method of diverting (just getting an op to connect you to the number) gets rid of both ANI and CLID. The ANI dis-appears completely, and the CLID is what is known as the generic paket. No info about you can be given from this packet. ANI and call logging. Call logging is done at your exchange and this shows all numbers you have dialled. So even if you dial 141 before dialling you can get snared by the caller log. Diverting only shows that you have made an operator call, and loads of people are dialling the op at once, so this is s good solution to that problem. OK, I can get rid of all my ANI/CLID/Caller Log info, but can I fake my CLID so that I look like somenone else? The good news is that you can with a little knowledge of CLID protocols, and maybe some programming knowledge. What you need is a program that can transmit given CLID information to CLID Units (the ones that show residential/business customers the number before they pick up) How these units work is that they listen on the line for a warning tone from the exchange, and then a modem recieves the CLID info before the fone rings. All this takes place in a fraction of a second. So all that is required is such a program. And the following method: 1) Divert through an op to call the number you wish (or dial 141 at least) 2) Wait for pick up, and when they go off hook, send the CLID packet 3) Do what you want How this looks at their end is as follows: 1) Fone rings and CLID unit says "Operator call" or "Number withheld". They then pick up the reciever (and possibly hear a "cheep") 2) The unit then says the fake number on its screen. This is perfect for 0800 numbers, because they have CLID units. Its also good for ISP's, and even certain telephone companies!! What won't be fooled is 1471, but if you've done it right then there will be no number there. Thats all I can think of now, maybe we'll see a good proggie spring up to help us soon!