1) There is a subscriber's device with GSM SIM card inserted. The operator always logs and records the device's connections from the nearest base station to the base station only at the time of incoming / outgoing calls, receiving / sending SMS, requesting access to the Internet
2) Each subscriber is logged and recorded without exception and this is done in any country of the world by all GSM communication operators
3) The IMEI of the phone, the service infa from the SIM card, the subscriber number from which the call originated / sms, the number of the subscriber to whom the call was sent / sms, the date and time of connection with the base station, the base station number, the coordinates of the base station, the base address stations and azimuth from the north to the subscriber's device at the moment of connection with the base station
4) Garbage open a criminal case or receive a court order (at the moment it happens that way, until 2011 everything was much easier and the cost of printing through the reds was $ 100-150) and on this basis they request a printout of the subscriber with the same number phone from the operator.
5) The operator catchs information from the logs first at the phone number, then on the phone received from the IMEI logs, while if the device was changing SIM cards, the report gets information on all the phone numbers for this IMEI