 system to which a network is connected and with which other devices can communicate. (2) The primary or controlling computer in a network. hotspot A location that enables Internet access from mobile devices (such as laptops and PDAs) without connection cables to networked services, usually through Wi-Fi. Hotspots are often found in restaurants, train stations, airports, cafes, libraries, and other public places. howler tone The tone that alerts a subscriber when a telephone is off the hook. HSCSD (High-Speed Circuit-Switched Data) A high-speed transmission technology that enables users to send and retrieve data over GSM networks at transmission speeds between 28.8Kbps and 43.2Kbps by enabling the concurrent usage of up to four traffic channels of a GSM network. HSDPA (High-Speed Downlink Packet Access) A key 3.5G standard that provides rates from 8Mbps to 14Mbps over a 5MHz bandwidth in W-CDMA downlink to support packet- based multimedia services. HSDPA enhances W-CDMA similarly to the way EDGE enhances GSM/GPRS. HSOPA (High-Speed OFDM Packet Access) A key 3.5G standard that incorporates OFDM and MIMO, promising to offer a 40Mbps download speed. HSPA (High-Speed Packet Access) The combination of HSDPA and HSUPA services. HSSI (high-speed serial interface) A physical-layer interface between a DTE, such as a high-speed router or similar device, and a DCE, such as a DS-3 (45Mbps) or SDH/SONET OC-1 HSUPA (High-Speed Uplink Packet Access) A key 3.5G standard that enables users transmit data upstream at a speed of 5.8Mbps. HTML (Hypertext Markup Language) A document standard that defines a simple logical structure including titles, headings, paragraphs, lists, forms, tables, and mathematical equations, as well as a language to specify hypertext links. HTTP (Hypertext Transfer Protocol) The standard mechanism used on the World Wide Web for the transfer of documents between server and client systems. HTTPS (HTTP over SSL) A Web protocol that encrypts and decrypts user page requests as well as the pages that are returned