I think you guys are worried about the wrong problem. The E911 stuff is still years off. Even when it is deployed, it will probably work only during a call, though this may depend on the exact method. In my opinion, idle cell registrations -- which are already standard cellular system practice -- represent the far more serious privacy threat. The cellular network uses registrations to locate mobiles so that page (incoming call) messages can be directed to the user's cell instead of being inefficiently "flooded" over the entire network. (I note that each AMPS paging channel is 10 kb/s while the usual one-way paging system operates in flood mode at something like .5 - 2 kb/s. But cellular phone calls have to go through in seconds, while pager messages often take minutes.) While these registrations are not quite as precise as the E911 locating stuff under discussion, they can be precise enough. They'll locate you to a given cell and sector, to say nothing of a given city. In many heavily populated places, cells are pretty small. And most importantly, registrations occur whenever the phone is on -- whether or not it's in a call. Even the most heavily used phones probably spend most of their time idle, and many less heavily used phones are probably idle for days at a time. While it would seem that a cellular carrier would have no reason to log these messages, many do. The main reasons, as I understand them, have to do with resolving roamer billing disputes and detecting cloning fraud. The FBI is already slobbering all over these registration logs and has been battling the CTIA to get them under CALEA -- even though Louie Freeh specifically disclaimed an interest in them during the Congressional hearings on CALEA. So far the CTIA has resisted. But knowing them, the problem is almost certainly about money and not anything as inconsequential as personal privacy. Phil