I might have been mislead by the use of IP, the handset is what is tracked and it usually is more precise than just what tower the device is associated with. It can include measurements taken from multiple towers, which can be derived from data needed for CDMA to even function, or it can include government mandated E911 information which is usually derived from an internal 4-channel GPS receiver. In theory this is only supposed to be used for E911 functions when the handset is in contact with a PSAP, but we have no way as the public to know what information from these systems are collected and stored or for how long.