The GSM MoU’s IMEI(International Mobile Equipment Identity)numbering system is a 15 digit unique code that is used to identify the GSM/DCS/PCS phone. When a phone is switched on, this unique IMEI number is transmitted and checked against a data base of black listed or grey listed phones in the network’s EIR (Equipment ID Register). This EIR determines whether the phone can log on tithe network to make and receive calls. To know the IMEI number the *#06# has to be pressed, the number will be displayed in the LCD screen; it is unique to a mobile phone. If the EIR and IMEI number match, the networks can do a number of things. For example grey list or blacklist a phone: 1. Grey listing will allow the phone to be used, but it can be tracked to see who has it (via the SIM information). 2. Black listing the phone from being used on any network where there is an EIR match.
DESIGNING FOR THE SNIFFER
As stated this proposal is about the detection of lost mobile phone and for this purpose we are designing a new device called the Sniffer. The sniffer device has to be designed precisely and size should be reduced for easy mobility for the purpose of detection. The device can be called as a mobile base station that includes the following important
1. Sniffer base station
2 .Unidirectional antenna
3 .Tracking software
SNIFFER BASE STATION:
The sniffer is a small base station, it includes transceiver section. It should operate at a frequency that is much different from the frequency of the current cell in which the operation of detection is being carried out. Some of the main important things are the frequency that has to be generated by the transceiver section is around 900MHz range which is a VHF range and it is necessarily to design the oscillator circuit for that frequency range .Another important is the cooling that has to be provided to the circuit while designing the circuit that is to be operated at 900MHz range of frequency. Hence proper design of base station is an important thing in the design of the sniffer. Mobile phones as well as the base station has low power transmitter is also transmitting at low power. The transmitter of the sniffer has to be a low power transmitter. This helps in the process of reducing the interference of the device with the devices that are in the other cells.