Downstream
28 May 2006
A transmission from a server to an end user.
DSL (Digital Subscriber Line)
28 May 2006
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).
DTMF (Dual-Tone Multi Frequency)
28 May 2006
The type of audio signals generated when you press the buttons on a touch-tone telephone.
Endpoint
28 May 2006
A SIP or H.323 terminal or Gateway. An endpoint can Call and be Called. It generates and terminates the information stream.
Firewall
28 May 2006
A system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.
Full Duplex
28 May 2006
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.
FXO (Foreign Exchange Office)
28 May 2006
The interface on a VoIP device for connecting to an analog PBX extension.
FXS (Foreign Exchange Station)
28 May 2006
The interface on a VoIP device for connecting directly to phones, faxes, and CO ports on a PBX or key telephone systems.
Gateway
28 May 2006
A network device that converts voice and fax calls, in real time, between the public switched telephone network (PSTN) and an IP network. The primary functions of an IP gateway include voice and fax compression/ decompression, packetization, call routing, and control signaling.
H.323
28 May 2006
ITU standard for real-time interactive voice and videoconferencing over LANs and the Internet. This standard is used for many Voice-over-IP applications, and is heavily dependent on other standards, mainly H.225 and H.245.