IT LOVER

26/03/2009

Some Thing about VOIP

Filed under: voip — pankaj kuamr @ 10:47 पूर्वाह्न

VOIP -> 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, including Cisco, VocalTec, 3Com, and Netspeak 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  What is a VOIP Phone

What are VoIP phones?
VoIP phones are telephones which connect to VoIP networks instead of to the PSTN.

  • VoIP phones with Ethernet connections
  •  
  • VoIP phones with Wi-Fi / 802.11 connections 
  •  
  • VoIP phones with dialup modem connections 
  •  
  • Software VoIP phones 

 

1. VoIP phones with Ethernet connections
A VoIP phone with an Ethernet connection is the easiest type of VoIP telephone to use. Instead of a standard telephone RJ-11 connector to plug into the PSTN, these phones have RJ-45 connectors to plug into Ethernet networks.

The Ethernet connection is used to connect these VoIP phones to the VoIP server or VoIP gateway.

2. VoIP phones with Wi-Fi / 802.11 connections
Wi-Fi (802.11) VoIP phones provide the same service as Ethernet VoIP phones, but they do it wirelessly.

A Wi-Fi enabled VoIP phone connects to a VoIP server or VoIP gateway through your existing Wi-Fi network.

3. VoIP phones with dialup modem connections
VoIP phones with dialup modem connections are very similar to VoIP phones with Ethernet connections.

Instead of connecting to an Ethernet network, these VoIP phones dialup over the PSTN to VoIP service providers.

Using a VoIP phone with a dialup modem connection requires a regular analog POTS telephone line, but enables long-distance and international calls to be made over VoIP networks, usually at a significant savings.

4. Software VoIP phones
Software VoIP phones turn your PC into a VoIP telephone.

Software VoIP telephones are less expensive than the choices listed above, if you already own a personal computer.

Hardware for Software VoIP phones
Software VoIP phones use the PC’s sound card, speakers or earphones, and microphone. This hardware works to emulate a telephone, even though this is not what the PC was designed for.

For better ease-of-use, many companies manufacture USB VoIP phones. These devices give your PC a normal-looking telephone handset or headset.

 

 

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