ell sites' base stations. In addition, each carrier must authorize every mobile handset before it's allowed on the network. Mobile devices constantly send out signals to the nearest mobile company's switch, essentially notifying the switch of their location. For example, Verizon has five major switches in the New England states that receive signals from Verizon mobile devices. Fiber-optic cabling connects each of these switches to cell sites at the mobile carrier's towers, which tracks cell sites. The signals carried over this fiber cabling indicates each mobile handset's cell site and tower location. Moreover, each new tower is tested before it is "turned up" to ensure that the nearest 911 call www.TechnicalPDF.com center can be reached when users dial 911 when they are within range of the cell site. Mobile switches and the large amounts of fiber- optic cabling are critical parts of all mobile networks and they all depend on power to operate. Mobile networks are not immune to power outages caused by storms and natural disasters. Lightning strikes and snow emergencies are particular challenges because they can knock out electricity to switches and cell sites. Outages can occur at cell sites not equipped with a back-up generator. Not all carriers have adequate backup. Some have battery backup for momentary power glitches and short outages lasting only a few hours. Adequate backup is a growing challenge because of the increased number of small cells and natural disasters. The Three Elemental Functions of the LTE IP The LTE IP Core functions as mobile providers' data centers. Traffic from hundreds of cell sites passes through a mobile carrier's core network. Signaling gateways that translate protocols for 3G networks are located in the core along with 4G equipment. The LTE core network, also referred to as the evolved packet core, routes this traffic to data networks, the Internet, other mobile carriers, and other cell sites within the carrier's mobile network. Equipment and software located in the core also perform