Glossary of Terms

Glossary of Terms

ATA (Analog Telephone Adapter)
An adapter that connects to a high-speed Internet connection. It simply turns an analog phone into an IP telephone.

Bandwidth
The amount of data that can be moved between to points in a given time period. For networks, bandwidth is usually expressed in bits per second (bps).

Circuit-Switched
A communication system that uses direct connections for a transmission. The most common circuit-switched network is a POTS system. The direct connection between two parties is great for speed but because there is a direct connection no other type of communication can use the connection at the same time.

Codec
Compression-decompression. In VoIP it is a voice compression-decompression algorithm that defines the rate of speech compression, quality of decompressed speech and processing power requirements. The most popular codecs in VoIP are ITU-T G.723.1 and G.729 (AB).

Compression
compression is used at anywhere from 1:1 to 12:1 ratios in VOIP applications to consume less bandwidth and leave more for data or other voice/fax communications. The voice quality may decrease with increased compression ratios.

Demarcation Point (dmarc)
The dividing line between a service provider’s area of responsibility and the end-customer’s area of responsibility. Traditionally, this dividing line is in a customer’s phone closet where a service provider’s circuit enters their premise.

DID (Direct Inward Dialing)
The ability to make a telephone call directly into an internal extension without having to go through the operator.

DSL (Digital Subscriber Line)
High-speed Internet service via existing copper phone lines.

Dynamic Jitter Buffer
A buffer in an ATA that collects, stores and shifts voice packets to the voice processor in predefined intervals to reduce any distortion in audio.

E911 (Enhanced 911)
Allows phone users to dial 911 and be connected to the closest geographic PSAP and displays the calling party’s physical address.

End-to-End Service Delivery
The approach to providing and supporting service everywhere it exists. This is in contrast to other service providers that stop supporting their service at the demarcation point (usually the phone closet where their circuit comes into a building). Our end-to-end service delivery means that our customers don’t have to worry about figuring out how to integrate our service into their network like they do with most every other service provider.

FXO (foreign exchange office)
The interface on a VOIP device for connecting to an analog PBX extension.

FXS (foreign exchange station)
The interface on a VOIP device for connecting directly to phones, faxes, and CO ports on PBXs or key telephone systems.

Hosted PBX
The service which provides all the same functionality (plus new, advanced features) traditionally derived from an on-site PBX – but delivered over the internet and housed in a secure, redundant, disaster-proof environment.

IP Centrex
IP Centrex delivers such services as call hold, call transfer, last number look-up and redial, call forward, three-way calling, but does it on a packet-based network. Hosted PBX, Virtual PBX, and VOIP Phone Systems are all synonyms for IP Centrex.

IP Telephony
The transmission of voice and fax phone calls over data networks that use the Internet Protocol (IP). IP telephony is the result of the transformation of the circuit-switched telephone network to a packet-based network that deploys voice-compression algorithms and flexible and sophisticated transmission techniques and delivers richer services using only a fraction of traditional digital telephony’s usual bandwidth.

LAN
A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link and typically share the resources of a single processor or server within a small geographic area (for example, within an office building).

Latency
Also referred to as Delay. The length of time a Packet takes to travel from source to destination. Latency and Bandwidth define the speed and capacity of a network.

Packet
In data communication, the basic logical unit of information transfer.

PBX (Private Branch eXchange)
An on-site telephone switching system located at commercial premises that interconnects telephone extensions to each other as well as to the outside telephone network.

POTS (Plain Old Telephone System)
The original copper line phone system that uses switches to route calls.

PRI
Primary Rate Interface: an ISDN service that provides 23 64-Kbps B (Bearer) channels and one 64-Kbps D (Data) channel (23 B and D).

QoS(Quality of Service)
Measure of performance for a transmission system that reflects its transmission quality and service availability. Standards based QOS for VoIP usually involves the implementation of ethernet standards 802.1p and 802.1q at layer 2.

SIP (Session Initiated Protocol)
SIP is one of several underlying signaling protocols that can be used for VoIP – the best protocol due to its flexibility, ubiquity, and reliability. SIP can establish sessions for features such as audio/videoconferencing, interactive gaming, and call forwarding to be deployed over IP networks, thus enabling service providers to integrate basic IP telephony services with the Web, e-mail, and chat services. In addition to user authentication, redirect and registration services, SIP Server supports traditional telephony features such as personal mobility, time-of-day routing and call forwarding based on the geographical location of the person being called.

Softswitch
(Also called a Proxy Gatekeeper, Call Server, Call Agent, Media Gateway Controller, or Switch Controller) Software used to bridge a public switched telephone network and voice over Internet by separating the call control functions of a phone call from the media gateway (transport layer). Softswitch performs call control functions such as protocol conversion, authorization, accounting and administration operations.

T-1 (also known as DS-1)
A digital transmission link with a capacity of 1.544 Mbps (1,544,00 bits per second). This link can handle 28 point-to-point DS-0s, or 24 “DS-0s” for 24 voice conversations.

T-3 (also known as DS-3)
A digital transmission link with a capacity of 44.736 Mbps. This link can handle 28 DS-1s.

Trunk
A communications channel between two points, typically referring to large-bandwidth telephone channels between switching centers that handle many simultaneous voice and data signals.

Trunking
Trunking means that several connections in a network may be established simultaneously, and that setup of connections proceeds automatically using the channels available at the time in question. In this way many users may share a few connections, and if the number of connections is increased, the capacity of the network is increased more than proportionally. This means that an optimal trunking effect is obtained in very large networks.

VoIP (Voice Over Internet Protocol)
A telephone service that uses the Internet as a global telephone network. Voice information is transmitted in the digital form in packets.

Virtual PBX
The service which provides all the same functionality (plus new, advanced features) traditionally derived from an on-site PBX – but delivered over the internet and housed in a secure, redundant, disaster-proof environment.

VPN (Virtual Private Network)
Enables IP traffic to travel securely over a public TCP/IP network by encrypting all traffic from one network to another. A VPN uses “tunneling” to encrypt all information at the IP level.