s. The first source of voice subscriber business is a base of new subscribers. Wireless telephone demand is still growing as we write this in 2002, and we expect that growth to continue. The rate of growth is declining as the market for wireless telephony is sat- urating, but there are still more cell phones each month. The CDMA air interface offers an efficient medium for offering lower rates to attract new subscribers. It is im- portant to realize that in Europe and America, these are not actually new subscribers to telephone service but rather people who are adding wireless service to landline ser- vice or replacing landline service altogether with wireless service. The use of cellular telephones, in part, will be calls that would have been landline and are now wireless and also will be, in part, calls the subscriber would not have made before but will make now with a cellular telephone. The second source is churn from other services from the same wireless vendor. Churn is the tendency of customers to move from one service to another. Since the CDMA air interface is more efficient than frequency division multiple access (FDMA) and time Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Estimating Wireless Telephone Demand Planning for CDMA Capacity division multiple access (TDMA) technologies, when existing subscribers decide to re- place their old cell phones or when they want more features, we have a chance to switch them to CDMA service that can offer higher quality, lower rates, or both. As the mar- ket for new subscribers dries up, technology migration will become the dominant source of new CDMA voice subscribers. The third source is competition from other vendors of wireless telephone service in the same area. Lower rates can attract price shoppers, and higher quality of service can tip the balance for subscribers who are less price-sen