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.

BPL (Broadband over Power Lines): A system that delivers high-speed Internet access over power lines.

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 (Compressor/Decompressor): A software component that compresses an audio or video file.

Compression: VoIP uses various levels of compression to send voice over an IP network. The highest levels are as high as 12:1. A higher compression ratio is used for smaller bandwidth connections.

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 cell phone users to dial 911 and be connected to the closest geographic PSAP. Currently, VoIP services do not have access to E911.

Expandable Phone: A phone system where one phone is plugged into a phone jack and the other phones operate off a signal from the main base station or phone.

FCC (Federal Communications Commission): The regulator of the telephone and telecommunications industries in the United States. Right now there is very little regulation of the VoIP industry.

IP (Internet Protocol): The large group of specifications that define how data is transmitted over a data network.

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.

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

PSTN (Public Switched Telephone Network): Traditional telephone lines and the infrastructure associated with it.

Ring List: A list created for VoIP call hunting. Numbers listed on the list will be dialed if the number before it is not answered.

TCP (Transmission Control Protocol: A protocol used in conjunction with IP to send information over the Internet in the form of units.

UDP (User Datagram Protocol): A stateless and connectionless protocol that runs on top of IP networks.