| 21st Century Network: | The network which will eventually replace the PSTN. Developed in the UK by BT, it is also called the C21N. |
| ADSL: | Asynchronous Digital Subscriber Line. A means of achieving broadband access to the Internet, using conventional copper telephone cables. The Asynchronous part of the name refers to the fact that the bandwidth down from the Internet is greater than the bandwidth up from your computer to the Internet. |
| Analogue Line: | Also called a Land line or STD line. Analogue lines do not use Digital transfer of voice information. |
| ATM network: | The BT Asynchronous Transfer Mode Network is what permits contact between the BT local exchange and the Home gateway. |
| Broadband: | Name of an Internet connection usually operating at more than 512Kb down from the Internet. Can be delivered via ADSL or Cable. |
| BSC: | Base Station Controller, used by tranceivers to network the signals in a mobile network. |
| C21N: | The 21st Century Network, |
| Cab: | Short term for Cabinet. A roadside box which contains an access point to phone lines from houses and buildings in the locality. |
| Cable: | Short term for a telephone and broadband line using Fibre optic technology. |
| CAT 5: | Category 5 is the name of the network wiring for most local area networks. It permits data transfer in an IP environment at speeds around 100 Mbps. |
| CAT 5e: | A modified version of CAT 5 allowing speeds of up to 1000Mbps. |
| CAT 6: | A new cable specification enabling speeds of 1000Mbps. |
| Cell: | The name given to a region in a cellular network which has a Transceiver mast which lets mobile phones communicate. |
| Cell Phone: | Another term for Mobile phone. |
| Cellular Network: | The phone network based on a group of interlinked cells |
| CODEC | Compressor / Decompressor or Coder / Decoder. The hardware or software that converts audio (voice signals) into digital data for transmission across an IP network. There are several standards that exist to control the quality of conversion (G.711, G.726, G.729, G.723.1). |
| Convergence: | The coming together of Computers, IP, and telephony in a |
| DCCE: | Digital Cell Centre Exchange. Links all of the local DLSU's to form what is called the Local Network. |
| DLSU: | The local exchange is known as a DLSU (Digital Local Switching Unit). |
| DMSU | Digital Main Switching Unit Connects DCCEs to the trunk Network (ie the whole of the UK) |
| E1 Line: | a 2Mb digital line useable for telephony or data transfer. |
| Exchange: | A service run by the phone company for the public, the Exchange automatically routes calls between phones using telephone numbers to control the routing. |
| Fibre: | Short term for Fibre Optic Cable. A cable which transmits laser light modulated to carry telephony or data services. Fibre optic cable is more reliable than copper pairs. |
| Firewall | A device that provides intrusion detection with the aim of protecting information and devices on a private network from devices or users outside of that network |
| Gateway | A device commonly found were two dissimilar networks connect. Gateways are like translators enabling two different networks to talk to each other, for example an IP telephony gateways might let an IP enabled telephony system connect to the analogue PSTN network. |
| Hub | A device that passes network packets between network segments on a Local Area Network (LAN). ( see Switch) |
| IMS: | Integrated Mobile services is the convergence of email, voice, fax, images and video on mobile phones. |
| IP: | Internet Protocol |
| IP Hardphone: | A purpose built phone that can be used for VoIP. |
| IP Softphone: | A PC with an application for accessing VoIP. |
| ISDN: | Integrated Services Digital Network or Isolated Subscriber Digital Network. A more efficient system than analogue telephony, with digital connection capability providing Internet / IP access |
| ISDN2 | 2 channel 64 Kb ISDN |
| ISDN30 | 8 channel 64 Kb ISDN |
| ISP: | Internet Service Provider. Company which provides a range of Internet services, such as broadband access, domain access, email etc. |
| Land line: | Common term for a standard telephone connection where 2 wire complete a circuit between the two people talking. ( also see Analogue Line). |
| LAN: | Local area network. A network of computers connected by wireless or Cat 5 wiring, usually in a single building. |
| Leased line: | A telecoms line enabling very high bandwidth between two points. |
| Mobile: | Shortened term for Mobile phone. A battery powered portable phone which can communicate with other mobiles in a cellular phone network |
| MSC: | Mobile Switching Centre. Used to connect a range of BSCs in a mobile network to the PSTN. |
| NAT: | Network Address Translator. |
| Private Network: | A network which cannot be accessed by external users without security clearance. The Internet is a Public network. Some private networks use the Internet through a service called VPN. |
| PABX | Private automatic branch exchange. See PBX. |
| PBX: | Private branch exchange This is a telephone exchange that serves a particular business or office, rather than a one which a telephone company runs for the general public. PBXs are sometimes called PABX |
| POTS: | The Plain Old Telephone System ( also called the PSTN) |
| PSTN: | The Public Switched Telephone Network |
| QoS: | Quality of Service |
| RCU: | A large wiring connector which brings together many CAB box outputs (particularly in cities or large towns). |
| SDSL: | Synchronous Digital Subscriber Line. A means of achieving broadband access to the Internet using conventional copper telephone cables where the bandwidth down from the Internet is the same as the bandwidth up from your computer to the Internet. SDSL usually has a premium cost in comparison to an ADSL line. |
| SIP | Session Initiation Protocol. |
| SIP Client | A phone, computer or PDA, or other piece of hardware that can communicate through a SIP session. |
| SIP Proxy Server | A server which provides a connection service to initiate and terminate communication between SIP clients. |
| SIP Registrar Server | A server which tracks the IP addresses of SIP Clients in a particular domain. |
| SIP Redirect Server | A server which tacks the SIP registrar servers in different domains. |
| STD line: | This is called Subscriber Trunk Dialling and is the means by which users on land lines can call any number in their country or internationally, without having to use an operator for connection. |
| STUN: | Simple Traversal of UDP through NAT |
| Switch | Sometimes called a Switched Hub. This is a device that intelligently directs the flow and determines the route of network packets between network segments on a Local Area Network (LAN). |
| Telephone Exchange: | A telephone exchange (sometimes called a telephone switch) is a system of electronic components that connects telephone calls. |
| Telephone Switch: | See Telephone Exchange |
| Transceiver: | A radio transmitter-receiver, often found in a Cellular network mast. |
| TURN: | Traversal Using Relay NAT |
| VoIP: | Voice over IP |
| VPN: | Virtual Private network. A means by which businesses can achieve secure communications between two LANs or from home users to a main business LAN. |
| WAN | Wide Area Network. The collective name given to a group of connected computing devices located geographically remotely from each other. |
| Wireless: | The name given to network communications without wires. Usually wireless access is within around 30 to 100 metres from the access point. Some access points connect to wired networks. Some are routers which connect to the phone system to give the broadband Internet access. |
