gnu@hoptoad.UUCP.UUCP (06/04/87)
In article <8705312136.AA01347@mimsy.umd.edu>, mgrant@MIMSY.UMD.EDU (Michael Grant) writes: > The Electronic Serial Number is an 8 digit Hexidecimal number. It is not > easily changed. Both the MIN, (Mobil Id Number, your phone number) and the > ESN are sent out when you press the send key. Your MIN is easily changed > by reprogramming your phone, but the ESN is not easily changed. To change > your phone number, both the phone, and the cell system must be changed. The whole thing is pretty silly. Each unit has a serial number and the serial number is "supposed to be" impossible to change. Actually in many systems it is in a PROM in a socket, so no biggy. Even if it was impossible to change, it's not impossible to change the ROMs that hold the program that runs the phone, so you could always reprogram it to ignore the ROM. You could embed the whole phone in epoxy, but who would buy a $2000 phone that you have to throw away if any little thing breaks? The best deal would be to make a program ROM where if you put it in this mode, it would listen on the control channel for phones making calls or answering rings, and save away 10 or 20 of their phone number/ serial number pairs. Anytime you wanted to make a call, it would pick one at random and pretend to be that phone. The load on any individual's bill would be light enough that you'd be hard to catch. This would not let you receive calls for free, but I seem to recall some scheme for that, too. Geoff Goodfellow, Bob Jesse, and Andrew Lamothe published a paper on this in the November 1985 issue of Personal Communications Technology magazine (FutureComm Publications Inc., 4005 Williamsburg Ct., Fairfax, VA 22032, 703/352-1200). The cellular phone standard is called "EIA IS-3-B" though I think they recently upgraded it to "-C". You can get a copy from Global Engineering Documents (call 800 information). It is not lucid but it is readable if you flip around a lot and think about it.