Whether you feel like being a stealthy spy or keeping tabs on your kids as they embark on the great unknown, a portable tracking device could be your solution. These gadgets are often quite pricey; however, you can make your own tracking device with a mobile phone.
Purchase a compact GSM mobile phone that has silence and auto-answer functions. An external antenna is a bonus for better signal reception.
Open the battery compartment of the phone. Remove the battery. Look for the IMEI number and write it down. Some phones with LCD screens will display the IMEI number when your dial the code *#06#. If you're still having trouble, contact your phone vendor.
Purchase phone service for the phone. This can be fairly cheap, but find something that provides you with a large roaming coverage area and reliable connections. Make note of the new number. Keep this number with your IMEI number.
Turn on the auto-answer and silence features. Turn off any vibration and lighting effects. Use the phone's manual to learn how to keep the phone totally silent. Activate the keylock and wrap all lights and keys with black electrical tape.
Place the mobile phone with the person or thing you wish to track. This can be your car or the backpack of your small child. If you're planning to use the device in a car as an antitheft tool, a good place to mount it is the underside of the driver's seat.
Test the phone-turned-tracking device. Have a friend in another room talk while the phone device is nearby. Call the phone device from another phone. If the device is working, you should be able to hear the person talking. They should have no indication that you just called.
Contact the police department and phone service provider to find a lost child or stolen car. Inform them of the tracking device and give them the IMEI and phone number. They will use the information to pinpoint the location of the device using Global System for Mobile Communications towers. By calling the device, you or the police will have the added benefit of hearing what's being said on the other end, providing better knowledge of the situation.
Acquaint yourself with state and federal laws before using a mobile tracking device on a third party. In most cases it is illegal to track someone without his consent.