traight cord (cable), usually gray or a translucent gray called silver satin. Typical lengths are 6 feet, 9 feet, 13 feet and 25 feet. This cord sometimes has a modular connector at each end, one plugging into a jack opening on the telephone and the other plugging into a jack opening in the wall. In some cases the mounting cord is wired directly to the telephone or the wall or to both and cannot be unplugged. The dial pad. Also called the keypad, touch-tone pad, touch- tone buttons or DTMF pad ("DTMF" stands for dual tone multi-frequency, referring to the touch-tone signals). Most telephones use the DTMF method for sending a telephone number to the telecommunications service provider. The lo- cal telephone company central office and the business telephone system (PBX) must have the capability to process 6 52 The Telecom Handbook CHAPTER 1 these tones. The telephone is equipped with the dial pad having 12 buttons that represent the numbers 0 through 9 and the symbols * and #. Pressing one of the buttons causes an electronic circuit to generate two tones. There is a low-fre- quency tone for each row and a high-frequency tone for each column. Pressing button number 5, for example, generates a 770-Hz tone and a 1,336-Hz tone. By using this dual tone method, only seven tones produce 12 unique combinations. The frequencies and the dial pad layout have been interna- tionally standardized, but the tolerances for variations in frequencies may vary in different countries. The touchtone signals are used not only to dial telephone numbers, but also to interact with Voice Processing systems such as Voice Mail, Automated Attendant. (for Sales press 1, for Service press 2, etc.) and Interactive Voice Response. Some telephones may have a round rotary dial, but this is becoming less common. The signals sent out by a rotary dial telephone are called dial pulse. Rotary dial telephones are still in use. In general, their dial pulses are not recognized by voice processing systems. Touchtones on A Rotary Outside Line Some telephones h