Exercise 5. A simple telephone system consists of two end offices and a single toll office to which each end office is connected by a 2-MHz full-duplex trunk. The average telephone is used to make four calls per 8-hour workday. The mean call duration is 8 min. Twenty percent of the calls are long distance (i.e., pass through the toll office). What is the maximum number of telephones an end office can support? (Assume 5 kHz per circuit.) Explain why a telephone company may decide to support a lesser number of telephones than this maximum number at the end office