es the handset and the caller at the other end does not sense that he is on a speaker. This is sometimes used for training staff members on how to handle particular types of calls. Speakers may also be used for internal intercom communication only, where someone in on the same premises can call you and his voice will be projected over the speaker. Some systems will allow you to answer back hands-free while others will not. Not surpris- ingly, this feature is known as hands free answer back! j. Message waiting indicator. If the system is working with a Voice Mail system, this lamp or LCD indicator lets you know that you have a message waiting in your Voice Mailbox. There 10 The Telecom Handbook CHAPTER 1 may also be a message on the display of the telephone such as MW for "message waiting." Any of these may also indicate a message waiting at the reception desk or message desk if there is no Voice Mail. Although this use is less common most tele- phone systems enable a receptionist to manually activate a message-waiting indicator on any telephone in the system. In some systems, the message waiting indicator is a button that, when pressed, will automatically connect you to the Voice Mail system or receptionist to retrieve your messages. k. Base of the telephone; telephone housing. This is gener- ally a molded plastic casing designed to house a specific type of telephone. Faceplate or Face Layout. Most telephones that work with business telephone systems enable you to print a layout of the front (face) of the telephone including the extension num- bers and system features that correspond to each button. This printed layout may slip into place over the buttons and under a clear plastic cover that is often called the faceplate. Telephone Functions Depend Upon the System Another way to define the telephone is to describe its func- tions. Remember that what a telephone is able to do depends in a large part on the system to which it is connected. Some telephones are connected via cable in the walls to a business telephone