tocol, SIP. www.TechnicalPDF.com This refers to the impersonation of a legitimate IP telephone or other device by a hacker. A proxy server screens communications between endpoints to verify that the called and calling parties are who they say they are and that no virus will be sent. A proxy server might sit between a VoIP server and external devices that request an audio conference or videoconference session. This is referred to as intermediating sessions. Proxy servers are also used between IP telephones and the Internet. Quality of Service guarantees a particular level of service. To meet these guarantees, service providers or IT staff members allocate bandwidth for certain types of traffic. Real-time Transport Protocol is an Internet Engineering Task Force (IETF) standardized protocol for transmitting multimedia in IP networks. RTP is used for the "bearer" channels-the actual voice, video, and image content. SIP is commonly used for the signaling to set up and tear down sessions. Skinny Client Control Protocol is a Cisco proprietary signaling protocol for sending signals between devices in Cisco telephone systems. It is also referred to as "Cisco Skinny." Session Initiation Protocol establishes sessions over IP networks, such as those for telephone calls, audio conferencing, click-to-dial from the Web, and instant messaging exchanges between devices. It is also used to link IP telephones from different manufacturers to SIP-compatible IP telephone systems. It is used in landline and mobile networks. www.TechnicalPDF.com Part II. Industry Overview and Regulations Chapter 3 Competition, Industry Structures, and Regulations www.TechnicalPDF.com 3. Competition, Industry Structures, and Regulations In this chapter: Introduction The 1984 Breakup of AT&T Regulatory Issues The State of the Industry-Consolidation via Mergers Non-Traditional Competitors: Alphabet, Apple, Amazon, Facebook, Twitter, Snapchat, and Microsoft Appendix INTRODUCTION The United States is fortunate to have high-capacity broadband networks through