devices, usually Network (VLAN) personal computers or VoIP devices, whose addresses are programmed as a group in Layer 2 switches. This segre- gates them from the rest of the corporate network SO that all devices in the same VLAN can be given a higher priority or level of security. They are programmed as a separate LAN but are physically connected to the same switch as other devices. Wide Area Network A group of data devices, usually LANs, that communicate (WAN) with one another between multiple cities. Part // Industry Overview Chapter 3 Competition, Industry Structures, and Regulations This page intentionally left blank Competition, Industry Structures, and Regulations In this chapter: Introduction The 1984 Breakup of AT&T Regulatory Issues The State of the Industry Nontraditional Competitors: Amazon, Apple, Google, Microsoft, and Netflix Appendix Competition, Industry Structures, and Regulations INTRODUCTION Mob networks have had a growing impact on business and residential life as their capacities and speed have improved. Until the early 2000s, mobile networks carried mainly voice; now, they support a growing volume of instant messages, e-mail, and applications, as well as Internet access. Business people and consumers alike are able to easily carry around their most important voice and data communications informa- tion in lightweight smartphones and tablet computers. Today, staff members can create proposals, check on orders, and conduct most business functions from within their office building, while away on a business trip, or from a home office. For carriers, most of which have experienced large losses in home telephone ser- vices, mobile services are a growing percentage of revenue. However, their success in attracting customers who transmit large amounts of data has increased pressure to upgrade networks to carry more data on finite amounts of spectrum. Spectrum, as the word is used with respect to the telecommunications industry, is the range of all radio frequency signals (invisible electromagnetic wa