ATT Cell Phones

IDENTIFICATION EQUIPMENT AND SUBSCRIBERS (GSM)
SIM  – GSM phones use a microchip called Subscriber Identity Module (SIM). SIM is used to store configuration data on the phone, etc. on existing subscription. Each card is activated by a unique identification number, once activated, the identification number is registered and is related to the network card that has been activated.

As you may know, there are mobile networks that allow you to use a cell phone without a SIM card. Phones that do not use the card have data loaded into them.

IMEI (International Mobile Equipment Identity) is a number composed of 15 digits that identify the GSM standard used equipment, phone. You can see it on the phone’s battery. This identification number is entered into the phone by the manufacturer, and when the phone tries to access a network, the IMEI is compared with data from a database, thereby being possible to determine whether or not the phone is stolen.

IMSI  (International Mobile Subscriber Identity) is composed of a 15-digit number that is stored on the card and the user is assigned by the telephone operators. This code allows the operator to identify the number of telephone subscriber. Also, IMSI contains a code identifying the country in which the subscriber agreement.

TMSI (Temporary Mobile Subscriber Identity) is a number assigned by the network and is shorter than the IMSI. TMSI is used to hide the true identity of the user against those who would try to decode the transmitted signal containing IMSI code of the phone. By submitting regular and frequent TMSI, IMSI may be sent less frequently.

SID  (System Identification Code) is a unique 5-digit code assigned to each mobile operator. The mobile phone  switched operations are being conducted to identify the network on a control channel between the phone and base station. If the SID received a call from the network within range of which is found does not match that of the phone when the phone shows no signal.

If the two SID’s match, the phone is integrated into the network and can make calls. In the process of identification, mobile phone sends a request for registration in the network, thereby switching center which has a responsibility to communicate with the base station, the phone knows exactly the position of the equipment by the application. The same switching center establishes an emission rate phone if it performs a call.

How phone jamming works ?  -Mobile phones have low emissivity. Many of them are able to deliver signals to 0.6 watts and 3 watts. Because the power is small, useful signal does not reaches too far outside the cell’s operating at one time to the phone. This is the secret that allows operation of the system of mobile cells.