Telephone Privacy? Caller ID & Telemarketers Telephone subscribers can select to receive optional services from their telephone company. The services of interest here deliver information about the caller to the called party. For normal consumers, the caller's phone number is displayed on a special Caller ID device. For businesses, the caller's phone number can be collected by a computer; the computer can pull up a customer file for the person answering the phone to review even before they answer the phone. Of course, business can store your phone number and transaction information for later use or for sale to other interested parties. The telephone company can transmit varying amounts of information to the called party. The typical options include: Calling Number Delivery Calling Name Delivery Calling Name and Number Delivery When your telephone is set up, it automatically allows transmission of your telephone number to called parties. For various reasons, you may not want to transmit your phone number to others. For example, attorneys, medical professionals, teachers, and others may make business calls from their home. By using a reverse directory, a called party can often pinpoint your address by knowing your phone number. Some people do not wish to be called by telemarketers. They resist giving information about themselves and their locations unless required. Don't Automatically Give Your Phone Number There are two ways to defeat the transmission of your phone number to called parties. Call Blocking The first way is to block the transmission on individual calls. Typically by punching *67 (depending on your telephone company) immediately prior to dialing the remainder of the phone number you can block the sending of your phone number to the called phone. You need to prefix the phone number with *67 each time you want to block sending your phone number to the called party. Line Blocking By making a request to the phone company (in some places the public utilities commission) you can block the sending of your phone number on all calls. If you have line blocking, you may choose to send your phone number to the called party by punching *82. This unblocks "line blocking" for that call only. The telephone companies do not like to advertise the number of people choosing line blocking. Line blocking reduces the value of the Caller ID service. Although over half the phones in California are unlisted/unpublished, the FCC determined that line blocking should not automatically be given to these numbers; rather the FCC reasoned that Caller ID transmission with a per call blocking standard would be best for the economy. Anonymous Call Rejection Some phone lines automatically reject calls that have blocked sending their phone number. This service, Anonymous Call Rejection, automatically shuttles calls using "call" or "line" blocking to a recording indicating that the number your are called does not accept calls from blocked numbers. The called telephone does not even ring when a blocked caller attempt to make contact. Beware of 700, 800, and 900 Area Codes When you dial (700), (800), or (900) area code numbers you are transmitting your own phone number to the called party. This is because a different technology is used, called Automatic Number Identification (ANI). Calls from a pay phone cannot be blocked. You also transmit your phone number when you dial the 911 emergency number. Cell Phones as Bugs New digital cell phones can be used to overhear your conversations. The new generation of digital cell phones can be set in an "auto-answer" mode in which they are silent and do not ring or beep and automatically put calls through. This mode is most useful in hand-free mode where a headset is used. However, this mode can also be used on some models without the headset accessory. In this case, a call to the phone would not be indicated by any sound, but would transmit all conversations in the vicinity. The cell phone could be your own (if you choose to use it in that way) or it could belong to someone else. A cell phone placed in a stragegic location could transmit conversations without any notice to the people being observed. Beware of ISDN Lines The Plain Old Telephone System consists of several components. At the home or office is an analog telephone. It transmits an analog signal to the local switching office where the signal is converted to digital. The digital signal is transmitted to the destination switching office where it is reconverted to analog. This analog signal is then transmitted to the telephone at the receiving end. An enhancement allows digital devices to be located at both ends of telephone communication. This allows several distinct signals to be transmitted simultaneously and greater bandwidth for communications. This Integrated Services Digital Network (ISDN) provides enhanced communications options. There are some studies that indicate that Integrated Services Digital Network (ISDN) lines can be taken "off hook" to allow the phone to transmit nearby conversations to the central switching station. This essentially means, if verified, that a national dial up telephone tapping capacity has been engineered into the ISDN system from the start. European Parliament: Scientific and Technological Options Assessment (STOA) Report: Modern communications systems are virtually transparent to the advanced interceptions equipment which can be used to listen in. Some systems even lend themselves to a dual role as a national interceptions network. For example the message switching system used on digital exchanges like System X in the UK supports an Integrated Services Digital Network (ISDN) Protocol. This allows digital devices, e.g. fax to share the system with existing lines. The ISDN subset is defined in their documents as "Signalling CCITT1-series interface for ISDN access. What is not widely known is that built in to the international CCITT protocol is the ability to take phones 'off hook' and listen into conversations occurring near the phone, without the user being aware that it is happening. (SGR Newsletter, No.4, 1993) This effectively means that a national dial up telephone tapping capacity is built into these systems from the start. Copyright © 2003 Robert Sherman Back to Cheap Long Distance