one. 12 The Telecom Handbook CHAPTER 1 Other manufacturers do not and the numbers and features are often written in pencil which looks very unprofessional, both for the installation company and the organization using the system. Telephones often start out neatly labeled, but get messy as changes are made to the features or extensions. Many busi- ness telephone systems are incorrectly labeled which makes them harder to use. Some telephones enable you to replace all button labels with a single sheet, which slips under the clear faceplate on the tele- phone. Others require that you create a single tiny little label and take off each individual button to replace the label. This can be time consuming when making many changes to a group of tele- phones. Others separate the labels into strips, with one paper strip per row of buttons. Color Trivia The single-line telephones that used to be supplied by the local Bell System company pre-1970 came in a variety of colors: white, black, red, ivory, pink, beige, blue, aqua, green and yel- low. In the 1980's the color choices for business and residence telephones were typically beige or ash, sometimes gray. Now black or charcoal is back as the new color of choice as organiza- tions grew tired of having the telephones always look like they needed a good cleaning. (Note that the desktop computer is slowly following suit with beige giving way to charcoal gray.) Expanding the Number of Buttons Some multi-line business telephones can change from ten to twenty buttons by "popping out" the button strips (called key strips) and inserting a panel with more buttons. Other business telephones can add one or more modules to add more buttons. On other systems the only way to get more buttons on the tele- phone is to purchase a new telephone. The Telecom Handbook 13 THE TELEPHONE Ringing One thing you can't tell by looking at a telephone is how the ring is going to sound. Yet this is a sound you are going to be listening to many times a day for many years. Telephone system manufacturers diff