SIP Connection
The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video and messaging applications. SIP is used in Internet telephony, in private IP telephone systems, as well as mobile phone calling over LTE (VoLTE). The protocol defines the specific format of messages exchanged and the sequence of communications for cooperation of the participants. SIP is a text-based protocol, incorporating many elements of the Hypertext Transfer Protocol (HTTP) and the Simple Mail Transfer Protocol (SMTP). A call established with SIP may consist of multiple media streams, but no separate streams are required for applications, such as text messaging, that exchange data as payload in the SIP message. SIP works in conjunction with several other protocols that specify and carry the session media. Most commonly, media type and parameter negotiation and media setup are performed with the Session Description P ...
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Signaling Protocol
A signaling protocol is a type of communications protocol for encapsulating the signaling between communication endpoints and switching systems to establish or terminate a connection and to identify the state of connection. The following is a list of signaling protocols: * ALOHA * Digital Subscriber System No. 1 (EDSS1) * Dual-tone multi-frequency signaling * H.248 * H.323 * H.225.0 * Jingle * Media Gateway Control Protocol (MGCP) * Megaco * Regional System R1 * NBAP (Node B Application Part) * Signalling System R2 * Session Initiation Protocol The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video and messaging applications. SIP is used in Internet telephony, in private IP telepho ...

Mark Handley (computer Scientist)
Mark James Handley is Professor of Networked Systems in the Department of Computer Science of University College London since 2003, where he leads the Networks Research Group. Education Handley received his PhD from UCL in 1997, under the supervision of Jon Crowcroft. Career and research While at the International Computer Science Institute (ICSI), Handley co-founded the AT&T Center for Internet Research, as well as the XORP open-source router project (2000). Handley is a contributor to Internet Engineering Task Force (IETF) standards and a member of the IETF Routing Area Directorate and the Transport Area Directorate. Previously he was a member of the Internet Architecture Board (IAB) and chaired the IETF Multiparty Multimedia Session Control working group and the IRTF Reliable Multicast Research Group. He is the author or co-author of 34 Request for Comments (RFCs), including the Session Initiation Protocol, Multipath TCP and a series of other network protocols. Awards and ...
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Presence Information
In computer and telecommunications networks, presence information is a status indicator that conveys ability and willingness of a potential communication partner—for example a user—to communicate. A user's client provides presence information (presence state) via a network connection to a presence service, which is stored in what constitutes his personal availability record (called a presentity) and can be made available for distribution to other users (called ''watchers'') to convey their availability for communication. Presence information has wide application in many communication services and is one of the innovations driving the popularity of instant messaging or recent implementations of voice over IP clients. Presence state A user client may publish a presence state to indicate its current communication status. This published state informs others that wish to contact the user of his availability and willingness to communicate. The most common use of presence today is to di ...
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Instant Messaging
Instant messaging (IM) technology is a type of online chat allowing real-time text transmission over the Internet or another computer network. Messages are typically transmitted between two or more parties, when each user inputs text and triggers a transmission to the recipient(s), who are all connected on a common network. It differs from email in that conversations over instant messaging happen in real-time (hence "instant"). Most modern IM application (computing), applications (sometimes called "social messengers", "messaging apps" or "chat apps") use push technology and also add other features such as emojis (or graphical smileys), file transfer, chatbots, voice over IP, or Videotelephony, video chat capabilities. Instant messaging systems tend to facilitate connections between specified known users (often using a contact list also known as a "buddy list" or "friend list"), and can be standalone applications or integrated into e.g. a wider social media platform, or a website ...
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Streaming Media
Streaming media is multimedia that is delivered and consumed in a continuous manner from a source, with little or no intermediate storage in network elements. ''Streaming'' refers to the delivery method of content, rather than the content itself. Distinguishing delivery method from the media applies specifically to telecommunications networks, as most of the traditional media delivery systems are either inherently ''streaming'' (e.g. radio, television) or inherently ''non-streaming'' (e.g. books, videotape, audio CDs). There are challenges with streaming content on the Internet. For example, users whose Internet connection lacks sufficient bandwidth may experience stops, lags, or poor buffering of the content, and users lacking compatible hardware or software systems may be unable to stream certain content. With the use of buffering of the content for just a few seconds in advance of playback, the quality can be much improved. Livestreaming is the real-time delivery of co ...
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Video Conferencing
Videotelephony, also known as videoconferencing and video teleconferencing, is the two-way or multipoint reception and transmission of audio and video signals by people in different locations for real time communication.McGraw-Hill Concise Encyclopedia of EngineeringVideotelephony McGraw-Hill, 2002. Retrieved from the FreeDictionary.com website, January 9, 2010 A videophone is a telephone with a video camera and video display, capable of simultaneous video and audio communication. Videoconferencing implies the use of this technology for a group or organizational meeting rather than for individuals, in a videoconference.Mulbach et al, 1995. pg. 291. Telepresence may refer either to a high-quality videotelephony system (where the goal is to create the illusion that remote participants are in the same room) or to meetup technology, which can go beyond video into robotics (such as moving around the room or physically manipulating objects). Videoconferencing has also been called "vis ...
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Public Switched Telephone Network
The public switched telephone network (PSTN) provides Communications infrastructure, infrastructure and services for public Telecommunications, telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telephony operators. These consist of telephone lines, fiber optic cables, microwave transmission links, Routing in cellular networks, cellular networks, communications satellites, and undersea telephone cables, all interconnected by switching centers which allow most telephones to communicate with each other. Originally a network of fixed-line Analog signal processing, analog telephone systems, the PSTN is now almost entirely digital in its core network and includes mobile and other networks, as well as fixed telephones. The technical operation of the PSTN adheres to the standards created by the ITU-T. These standards allow different networks in different countries to interconnect seamlessly. ...
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Internet Engineering Task Force
The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements and all its participants are volunteers. Their work is usually funded by employers or other sponsors. The IETF was initially supported by the federal government of the United States but since 1993 has operated under the auspices of the Internet Society, an international non-profit organization. Organization The IETF is organized into a large number of working groups and birds of a feather informal discussion groups, each dealing with a specific topic. The IETF operates in a bottom-up task creation mode, largely driven by these working groups. Each working group has an appointed chairperson (or sometimes several co-chairs); a charter that describes its focus; and what it is expected to produce, and when. It is open to all who want to particip ...
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Cellular Network
A cellular network or mobile network is a communication network where the link to and from end nodes is wireless. The network is distributed over land areas called "cells", each served by at least one fixed-location transceiver (typically three cell sites or base transceiver stations). These base stations provide the cell with the network coverage which can be used for transmission of voice, data, and other types of content. A cell typically uses a different set of frequencies from neighboring cells, to avoid interference and provide guaranteed service quality within each cell. When joined together, these cells provide radio coverage over a wide geographic area. This enables numerous portable transceivers (e.g., mobile phones, tablets and laptops equipped with mobile broadband modems, pagers, etc.) to communicate with each other and with fixed transceivers and telephones anywhere in the network, via base stations, even if some of the transceivers are moving through more than ...
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IP Multimedia Subsystem
The IP Multimedia Subsystem or IP Multimedia Core Network Subsystem (IMS) is a standardised architectural framework for delivering IP multimedia services. Historically, mobile phones have provided voice call services over a circuit-switched-style network, rather than strictly over an IP packet-switched network. Alternative methods of delivering voice (VoIP) or other multimedia services have become available on smartphones, but they have not become standardized across the industry. IMS is an architectural framework that provides such standardization. IMS was originally designed by the wireless standards body 3rd Generation Partnership Project (3GPP), as a part of the vision for evolving mobile networks beyond GSM. Its original formulation (3GPP Rel-5) represented an approach for delivering Internet services over GPRS. This vision was later updated by 3GPP, 3GPP2 and ETSI TISPAN by requiring support of networks other than GPRS, such as Wireless LAN, CDMA2000 and fixed lines. IM ...
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Mbone
Mbone (short for "multicast backbone") was an experimental backbone and virtual network built on top of the Internet for carrying IP multicast traffic on the Internet. It was developed in the early 1990s and required specialized hardware and software.Lewis, Peter H"Peering Out a 'Real Time' Window" ''The New York Times'', 8 February 1995. Retrieved 26 August 2009. Since the operators of most Internet routers have disabled IP multicast due to concerns regarding bandwidth tracking and billing, the Mbone was created to connect multicast-capable networks over the existing Internet infrastructure. History Mbone was created by Van Jacobson, Steve Deering and Stephen Casner in 1992 based on a suggestion by Allison Mankin. On May 23, 1993, '' Wax or the Discovery of Television Among the Bees'' was streamed over the Mbone, becoming "the first movie to be transmitted on the Internet." On June 24, 1993, the band Severe Tire Damage was the first to perform live on the Mbone. On November ...
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