Encryption & Misdirection
There are a few ways that come to mind on how to protect the information.
1) Encryption of the information, possibly something as simple as having a surrogate
phone # to act as an alias with this surrogate changing on a fairly frequent basis.
2) Have false information broadcast in addition to the real information which masks
the signal. The problem with this is the fact that phones have to work with
multiple systems which need access to the information and likely the system will
be cracked.
3) Have a more passive system so that if there is no phone call there is no tracking.
This is suboptimal since it would require an incoming call to alert many areas
to attempt to locate the phone, possibly overloading the capacity of the current
system as an entire region must be checked
