VoIP products are available from many Voip vendors and range from simple vop phones to complex routers and controllers. VoIP is not really a new concept and is now available on the market for many years, it's no more in testing mode. People don't know that much about a VoIP products. What are they, how do they work? Here is some information that can help.

VoIP products can be classified in three general categories:

- gateways and routers
- controllers
- end stations (such as phones)

Like everything else in the IT domain, every category has a specific function that it performs. And if you combine all the functions you will get a complete VoIP system.

VoIP Routers
Routers are (voip) devices that decide where the IP datagrams should go, between networks, from the source to the destination. Routers are inter-network equipments that help a LAN connect to a WAN; therefore the router's capability to ensure correctly handled high-priority traffic is very important. Since WAN speeds have generally less bandwidth than a LAN, proper packet queuing and priorization is in order to ensure good voice quality across the path.

VoIP gateway
With so many options available today, gateways are also capable of transcoding (changing the signal from one codec version to another so that the voip device can communicate with the rest of the network). A VoIP gateway is a voip device that connects the VoIP network to your public telephone network (PSTN). Depending on the type of the gateway, they are equipped with analog/digital interfaces in order to connect to your local telephone company.

VoIP controllers
VoIP controllers, also called IP PBXs, manage the VoIP network. IP PBX controllers are PC-based, running a standard OS (such as Microsoft Windows, Linux or Sun Solaris, but very different) with additional software to control the VoIP systems. Plus they are performing all the functions of a traditional PBX. These systems can provide APIs to extend vendor-provided or user-written features and functionality.

Hardware and software vop phones
There are two types of vop phones: hardware and software.

Software-only phones, or "soft" phones, use the PC's capabilities to communicate with other PC's over the Internet, by using the PC's sound card, CPU and network card as part of the phone's hardware, and thus, enable a PC to become an IP phone.

A hardware phone is a physical device, very similar to your common phone; it has a handset, dialpad, etc.
The only thing that is different from your ordinary phone is that it connects to an Ethernet network rather than a telephone network. vop phones are built with all the necessary hardware (and software) to digitize your voice (i.e., codecs) as well as setup and make calls (i.e., signaling and transport).

Jim Francisto
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