Electronic Snooping Into Your Cellular Telephone
Many consumers (some of them still sitting in federal prison) do not fully appreciate just how much information about their behaviors is stored in such things as their car's computer, their home or office's electronic telephone system, or their personal and networked computers and the associated servers. Often overlooked as an electronic tattletale is the most ubiquitous telecommunication device of the late 20th century: the cellular mobile telephone.
So commonplace have these little marvels become that we load them up with all sorts of personal contact information (including call logs, photos of children, homes, outings, etc.) and then discard them every year or two when a newer and more full-featured model hits the market. Some people, maybe most, go through the phones and dutifully use the erase or reset function before giving the phone away to the Women's Center or simply tossing it in the garbage. Believing they have cleansed the little beast of its incriminating, embarrassing, or maybe titillating information, they toss or donate it . And they leave behind a good deal of information for us electronic snoops. How much information? Read this Washington Post article titled Used Cellphones Hold Trove of Secrets That Can Be Hard to Erase (free registration may be required).
The proliferation of microprocessor memories in a wide range of devices including vehicles, appliances, utility meters, and telecommunications equipment has increased the probability that some of your private information will be compromised. At least with cellular mobile telephones, you can take steps to more completely reduce that probability. One reasonably accessible countermeasure is to contact the manufacturer of your phone and ask for specific instructions about how to completely erase and overwrite all the information you've put into the phone. You can also go to a website, WirelessRecycling.com, and get erasure instructions for some telephone models.
That's the good news.
The bad news is that from firsthand experience analyzing equipment and dealing with cellular telephone design engineers, I can tell you that companies will often not reveal all of the exploitable capabilities of their equipment. Most of today's cellular mobile telephones have chips containing features that are not marketed or user accessible but have been designed in to minimize future manufacturing costs. On more than one occasion we caught cellular telephone manufacturers denying an exploitable capability existed. Then we confronted them with their lie by showing them how we had done what they denied could be done.
The bottom line is this: If you have a cellular mobile telephone you want to discard and if it is imperative that no critical information be retrieved from it, first remove the battery, then use a very heavy hammer or a torch to totally destroy the telephone. Electronic erasure and overwriting helps, but it is not totally reliable. So don't rely on it!