vises software on servers with virtual machines. ILECs (Incumbent Local Exchange Carriers) The former Bell and independent telephone companies that sell local telephone service. This term differentiates incumbent telephone companies that were the providers of telephone service prior to 1996 from competitors such as Paetec, XO Communications, and tw telecom. IMS (Internet Protocol Multimedia Subsystem) Enables applications for voice, video, and online games to be stored, billed for, and accessed on a common IP platform available from mobile as well as wired networks. Indefeasible Right of Use (IRU) www.TechnicalPDF.com Long-term lease for fiber-optic cable runs. IRUs are analogous to condominium arrangements. One organization lays the cable and leases it to another carrier for its exclusive use. independent telephone company An incumbent local telephone company that was never a part of the former AT&T's Bell system. Examples of independent telephone companies are Frontier Corporation and Cincinnati Bell, Inc. instant messaging The ability to exchange e-mail in near-real time without typing in an address. Users merely click an icon representing the user to whom the message is intended, type a message, and then click Submit (or press the Return key) to send the message. intermodal competition Competition between services based on different media and technology. For example, mobile services compete with wireline services for local and long-distance calling. Cable TV companies compete with telephone companies such as AT&T and CenturyLin Internet The Internet-with a capital I-is an entity composed of multiple worldwide networks, tied together by a common protocol, TCP/IP. intranet The use of web technologies for internal operations. Intranets are used by organizations as a way to make corporate information and applications readily accessible by employees. An example is a corporate telephone directory that can be accessed by a browser. inverse multiplexer www.TechnicalPDF.com Instead of combining individual channels int