FAQ’S AND TERMINOLOGY

VoIP Introduction – What is VoIP?
VoIP (voice over IP - that is, voice delivered using the Internet Protocol) is a term used in IP telephony for a set of facilities for managing the delivery of voice information using the Internet Protocol (IP). In general, this means sending voice information in digital form in discrete packets rather than in the traditional circuit-committed protocols of the public switched telephone network (PSTN). A major advantage of VoIP and Internet telephony is that it avoids the tolls charged by ordinary telephone service.

VoIP, now used somewhat generally, derives from the VoIP Forum, an effort by major equipment providers, to promote the use of ITU-T H.323, the standard for sending voice (audio) and video using IP on the public Internet and within an intranet. The Forum also promotes the user of directory service standards so that users can locate other users and the use of touch-tone signals for automatic call distribution and voice mail.

In addition to IP, VoIP uses the real-time protocol (RTP) to help ensure that packets get delivered in a timely way. Using public networks, it is currently difficult to guarantee Quality of Service (QoS). Better service is possible with private networks managed by an enterprise or by an Internet telephony service provider (ITSP).

A technique used by at least one equipment manufacturer, Adir Technologies (formerly Netspeak), to help ensure faster packet delivery is to use ping to contact all possible network gateway computers that have access to the public network and choose the fastest path before establishing a Transmission Control Protocol (TCP) sockets connection with the other end.

Using VoIP, an enterprise positions a "VoIP device" at a gateway. The gateway receives packetized voice transmissions from users within the company and then routes them to other parts of its intranet (local area or wide area network) or, using a T-carrier system or E-carrier interface, sends them over the public switched telephone network.

VoIP Standards

• ITU-T H.320 Standards for Video Conferencing,
  
• H.323 ITU Standards
  
• H.324 ITU Standards
  
• VPIM Technical Specification

Asynchronous Communication

A data communications method in which bits are sent one after the other with a start and stop bit used for flow control. This as opposed to synchronous communication where blocks of data are transmitted using a synchronizing clock.

Audio Menu

A verbal choice provided by a recording over the phone. Audio choice menus are common in automated attendant, IVR and fax-on-demand systems. They are prompts for caller input. Audio menus can instruct you to speak commands or hit touch-tones as commands.

Audio Response Unit (ARU)

A computer telephony system incorporating voice store and forward technology. There are both passive and interactive ARUs. Passive ARUs simply play out messages. Interactive ones play messages based on input from callers.

Audio Teleconferencing

Or Audio Conferencing. The original technology used for audio teleconferencing was based on PBX conferencing circuits. Setting up conference calls through the PBX is cumbersome, voice quality degrades as the number of people on a call increases and there are capacity limitations. As a result, specialized conference bridges were developed to improve capacity and voice quality. Conference bridges, however, require trained operator intervention to schedule and invoke most features. As a result, individual corporations find the cost of ownership prohibitive, and the market for such products has been concentrated on service bureau providers. Today, PC-based systems combine the freedom of conference bridges. By installing a conference server on your voice networks, you can set up, attend, and manage your own conferences over any touch-tone telephone. Additionally, users can schedule meetings using desktop software from their e-mail systems, or from a Web browser.

Conference Bridge

A device used to connect multiple parties over the phone. A proctor or operator can man conference bridges, or the can be supervised. There are both stand-alone conference bridges and conference bridge functions built in to some PBXs (Private Branch Exchange). These systems have circuitry for summing and balancing the energy (noise) on each channel so everyone can hear each other. More sophisticated conference bridges have the ability to "idle" the transmit side of channels of non-speaking parties. Some conference bridges use "clVoxising" to idle or reject the input of touch tones or other signals.

Digital Subscriber Line

A high-sped digital switched service using existing copper pairs to connect subscriber CPE (Customer Premises Equipment) to the Central Office. DSL handles more data downstream (data flowing towards the subscriber) than upstream (towards the network).

E-1

The designation for the 2.048Mbps. ITU standard for Europe's 30-channel digital telephone service. It is the European version of T-1 (DS-1). The bandwidth is divided into two signaling channels (channels 15 and 31 starting from 0) and a thirty bearer (voice channels). A&B bit signaling (robbed bit signaling) is not used here. E-1 uses one of the control channels for signaling and the other for clock synchronization.

Fax Server

A computer based fax machine. Fax servers are "shared use" devices, typically installed on a LAN. Clients on the LAN can use the fax server from their PCs in much the same way they share a network-based (shared) printer. Faxes can be generated by users at their workstations and "printed" to the fax server for transmission. Likewise, fax servers can route incoming faxes to printers, file server directories or to individual users. Fax servers save users from having to print documents, carry them to the fax machine and subsequently wait for them to be transmitted after creating a cover page.

Frame Relay

In data communications, a packet switching method, that uses available bandwidth only when it is needed. This fast packet switching method is efficient enough to transmit voice communications with the proper network management.

Full Duplex

In telephony and data communications, the ability for both ends of a communication to simultaneously send and receive information without degrading the quality or intelligibility of the content.

Interactive Voice Response IVR.

In computer telephony, Interactive Voice Response is a horizontal application wherein computer-based information is accessed over the phone - with a telephone versus a computer. An IVR platform uses computer telephony components to translate callers' touch-tones or voice commands into computer queries after the callers hear an audio menu. For example: "Please enter your account number using the touch-tones on your telephone." These queries are then "fetched" by the IVR platform from the host computer. In some cases, the information resides in the same platform (self-hosted). The information is then converted into voice commands and then spoken over the phone to the caller. These spoken prompts can be pre-recorded, digitized speech messages that are then concatenated to form whole sentences. For example: "Your bank balance is five hundred and sixty-three dollars". The responses to the caller an also take the form of text-to-speech prompts. IVR systems can also be used for callers to change the information in a database instead of just "listen" to the information.

Internet

The current-day public and global computer network or "information super-highway." The Internet is an outgrowth and combination of a variety of university and government sponsored computer networks. Federal and private sector subsidies supported the DARPA-NET. NSFnet (National Sciences Foundation), and thousands of other subnetworks, which were used to do inter-agency research and communication. Today, the Internet is made up of millions upon millions of computers and subnetworks - almost entirely supported by commercial funds except in countries where deregulation has not occurred. The internet is the substrate and chief communications backbone for the World Wide Web (WWW), the "graphical interface" of the Internet.

Internet Telephony

Any means of transmitting the human voice (real time or close to real time) over the internet. There are several components: 1) On the client side, a multimedia-equipped PC with special client software will digitize your voice. This can be done with a voice modem or other voice encoding method; 2) A direct or dial-up connection to the internet allows your voice to be transmitted in packet form to its destination; 3) Connection with the far side is achieved by IP address search, common servers or beacons to identify the called party (and to "ring" that person's phone); 4) A similar arrangement on the far end completes the call and allows both parties to speak. There are also PSTN/Internet gateways that allow regular telephone callers to make Phone-to-Internet-to-Phone connections. There are PC-to-Phone connections and Phone-to-PC connections.

ISP

Internet Service Provider. A business that provides subscriber-based access to the Internet. Subscribers can be individuals or businesses. According to Jack Rickard, publisher of Boardwatch Magazine, ISPs operate at the fourth or lowest level of the Internet. At the third level, regional providers aggregate traffic from lower-order ISPs to the second, backbone level. The highest level in North America is the NAP (Network Access Point), which act as peer-to-peer interconnection points for the largest backbones. There are three "official" NAPs located in San Francisco, Chicago and Pennsauken, New Jersey. ISPs use both Internet Routers, Servers and Rack-Mounted modems to provide a variety of services including Web Site hosting, FTP service, e-mail accounts, unified messaging, audio and video broadcasting and in some cases - Internet Telephony and Fax Gateway service.

Messaging

In computer telephony, any means of message store and forward. This includes fax mail, voice mail and broadcast messaging. This horizontal application is the most popular of all other voice solutions. Messaging systems provide for the store and forward of "non-real time" communication. For example, a recorded voice message can be stored for later play back either locally or remotely, or a fax can be received and stored before it is re-transmitted to the ultimate recipient. Messages, then, can vary in content and media type - the distinction being that they are recorded or stored for pick up in the future. The time between original storage and retrieval of a message can be created and stored by a sales manager for later retrieval by multiple (worldwide) sales people. The sales staff can listen to the message at different times over an extended period. This is due to the nature if random retrieval by the recipients in their respective time zones. Messaging systems are a kind of "shared tenant" answering machine, because messages that were intended for as many as a thousand or more users can be stored and controlled by the same system. If a community of users agrees on some basic ground rules, messages can be shared, forwarded, and distributed to multiple recipients in the same fashion as e-mail.

Modem

Short for Modulator/Demodulator, Equipment that converts digital signals to analog signals and vice-versa. Modems are used to send data signals (digital) over the telephone network, which is usually analog. A modem modulates binary signals into tones that can be carried over the telephone network. At the other end, the demodulator part of the modem converts the tones to binary code.

Packet

A logically grouped unit of data. Packets contain a payload (the information to be transmitted), originator, destination and synchronizing information. The idea with packets is to transmit them over a network so each individual packet can be sent along the most optimal route to its. Packets are assembled on one end of the communication and re-assembled on the receiving end based on the header addressing information at the front of each packet. Routers in the network will store and forward packets based on network delays, errors and re-transmittal requests from the receiving end.

Packet Switching

A means of economically sending and receiving data over alternate/multiple network channels. The premise for packet switching is the packet, a small bundle of information containing the payload and routing information. Packet switching takes data, breaks it down into packets, transmits the packets and does the reverse on the other end. Packets can be sent in order and then be received in a different order - only to be put back in the correct order in seconds. There are slow packet switching networks, like the old SNA networks - and there are fast packet networks based on Frame Relay and ATM. Although traditionally used for data, packet networks, especially well-managed ones, are becoming suitable for real-time transmission of voice and video.

PBX

Private Branch Exchange, or PABX (Private Automatic Branch Exchange). In telephony, a PBX system behaves as a customer's premises over trunk lines (thus the term "branch"). At first, PBXs mimicked a small telephone company switchboard. Users would use an operator to take and make telephone calls to and from the PSTN (Public Switched Telephone Network). Over time, users were able to dial directly, without the use of an operator. Today, computer telephony platforms such as automated attendants are able to route incoming calls automatically, too.

POP

Point of Presence, equivalent of a local phone company's central office. The place your long distance carrier terminates your long distance lines just before those lines are connected to your local phone company's lines, or to your own direct hookup. Alternate Definition: Post Office Protocol. An Internet standard for the storage and retrieval of email messages

PSTN

Public Switched Telephone Network.

Real Time

A communication wherein any perceptible delay between the sender and receiver are minimal and tolerated. Regular telephone calls are real time. Point-to-point fax transmissions are "close" to real time. Voice messaging is in non-real time.

RJ-11

The designation for connecting a tip and ring circuit to a standard, modular, six-position jack. The green and red wires go in the middle (only) pair, and the outside positions of the connector are unused.

RJ-45

Eight-position modular connector, used for data transmission over standard twisted or flat pairs.

Service Provider

An addressable entity providing application and administrative support to the client environment by responding to client requests and maintaining the operational integrity of the server.