ies. And to a large degree, international enterprises depend on mobile communications to conduct business with mobile staff members and remote customers. Mobile networks are made up of vast landline networks, switches, and databases. The only portions of these networks that are actually wireless are between a user's device and the mobile network's antennas. Signals to and from antennas are transmit- ted over landline networks to a carrier's centralized core network. In addition to their wireless interfaces, mobile providers maintain complex wired networks as well as equipment and databases in core networks. Equipment in the core provides connections to billing systems, various databases, voice switches, and gate- ways. Gateways convert protocols in mobile networks to those compatible with public data networks and the Internet, and vice versa. The mobile core acts as a central site within which these functions are consolidated. Cellular technology has been transformed from the initial analog systems that were first installed in 1984 to the new, high-capacity digital networks that we use today. Each successive generation has higher capacities, can cram more signals given amounts of spectrum, and supports additional functions. Mobile networks are primarily based upon second-, third-, and fourth-generation standards. Additional interim standards that are transitions between generations are 2.5, 3.5, and pre-fourth- generation services. The following are the main protocols in mobile networks. The second generation, which is still the most common service worldwide, is digital and supports features such as caller ID, voicemail, and Short Message Service (SMS) for texting. Two examples include Code-Division Multiple Access (CDMA) and Global System for Mobile Communications (GSM). Third-generation services, which not all carriers have implemented, sup- port higher speeds and packetized data. Wideband Code-Division Multiple Access (WCDMA) and CDMA2000 are among these services. When they are fully implemented, fourth-genera