On Wed, Apr 2, 2008 at 10:02 AM, Sean Houston <[EMAIL PROTECTED]> wrote: > GSM & CDMA are both good and are both WAY Better then IDEN and TDMA.
Some clarification may be useful here: CDMA and TDMA technically refer to methods for multiplexing multiple calls into a single radio frequency channel, not mobile phone standards. But "CDMA" is popularly used to refer to a particular family of mobile phone standards which use CDMA. Likewise, "TDMA" is popularly used to refer to DAMPS, because DAMPS was the first mobile system to use TDMA. But GSM and IDEN are also based on TDMA. DAMPS is basically obsolete, and is being phased out -- I've read tower equipment has already been decommissioned in some areas. CDMA = Code Division Multiple Access TDMA = Time Division Multiple Access IDEN = Integrated Dispatch (or Digital) Enhanced Network GSM = Global System for Mobile communications (retcon; originally stood for some French consortium) DAMPS = Digital Advanced Mobile Phone System http://en.wikipedia.org/wiki/Code_division_multiple_access http://en.wikipedia.org/wiki/Time_division_multiple_access http://en.wikipedia.org/wiki/Digital_AMPS http://www.gsmworld.com/ http://www.cdg.org > First GSM and IDen phones cannot be disabled. To my knowledge, no phone can really be "disabled" remotely[1]. It's not like the carrier has an orbiting satellite which beams a self-destruct signal to the phone. What really happens is: All GSM, IDEN, and "CDMA" phones transmit the phone's hardware ID (IMEI/ESN) to the tower when they connect. The carrier can maintain a blacklist of stolen IDs. If a stolen phone shows up on their network, they can deny service, or call the cops -- or do nothing. That's entirely up the carrier. There's even a system for sharing the blacklist information among GSM carriers: http://www.gsmworld.com/using/security/ [1] Well, there are manufacturer-specific methods, like for Blackberry. But I don't know much about the technology behind them, or how well they work. > However if I have an AT&T GSM Phone ... and I find or steal another AT&T > phone, all > I have to do is put my SIM card in the phone and it's all good. It *is* easier to transfer service (user/phone number) with a SIM-based phone. As you say, all you do is swap the SIM cards. That applies equally well to legitimate users as criminals. (Draw comparisons to other kinds of freedom if you like.) However, once a phone is reported stolen, the carrier can disable the SIM and flag the IMEI as stolen. And, of course, any stolen phone is vulnerable to exploitation until it is reported stolen. > You cannot activate the phone unless it's attached to your account > and setup correctly. It is completely true that with a "CDMA" phone, you have to call the carrier to transfer service. There's no SIM to swap. And if the ESN of the phone is flagged as stolen, then the carrier will then know that someone tried to use the service account with a stolen phone. However, with GSM, if you put your SIM into a stolen phone, the carrier also has the capability of knowing the associated service was used with a stolen phone. So I'm not sure I see a practical difference. It may be that GSM carriers are less responsive about this stuff than "CDMA" carriers, but I'd like to see a verifiable source on that. > As far as theft of phones SIM Card based phones are stolen MUCH more often ... Source? Is that absolute or per capita? There are a *lot* more GSM phones in the world (it's an order of magnitude difference), so if that's just based on units stolen per year, of course there will be more GSM phones stolen. > ESN based phones have a much higher rate of being returned. Source? Assuming a thief steals a "CDMA" phone and discoveres it is of no use with his GSM SIM, why wouldn't the criminal just throw it away, rather than returning it? > Finally Cell phone providers don't care if the phone is stolen. That's generally been my experience as well. Actually, you can leave off the "if the phone is stolen part". In those scenarios I posted, I used the arrested thing for effect; call it "poetic license". I guess I should have known I would get called on it. -- Ben ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~
