Incoming Ring Tone to set the incoming ring tones, which are the tones a user hears when a call rings an extension. These tones are grouped into four ring tone Ranges (1 ~ 4), also called patterns, that consist of a combination of frequencies. (You assign a specific Range to trunks in Program 22-03 and to extensions in Program 15-02.) Within each range there are three frequency Types : High, Middle and Low. (Service Code 720 allows users to choose the Type for their incoming calls.) Each Type in turn consists of two frequencies and the modulation played simultaneously to make up the tone. These frequencies are determined by their Frequency Number selected in Items 1 and 2 (see below). In this program, you assign the two Frequency Numbers and Modulation for each Type, for each of the four Ranges. The chart below shows the default Frequency Numbers for each Type in each Range.