Choosing the right VoIP equipment

…that there are drivers available for the operating system(s) on which a user runs the soft phone software. USB phone sets are available from Yuxin, World Phone and Eutectics. (Note that USB phones are different from IP phones, which do not have to connect to a PC.)

Hard phones (IP phones)
A hard phone is a dedicated, self-contained computer that looks like a conventional phone and plugs into an Ethernet port on a router. It can communicate directly with the VoIP server or gateway and doesn't need to go through a PC, so a user doesn't have to install any software to use it. Hard phones cost a lot more than USB phones (typically starting at around $100, as opposed to less than $20 for a USB phone).

Hard IP phones are made by a large number of companies, including Texas Instruments, 3Com, D-Link and Cisco.

A special category of hard phones has a built-in modem in place of an Ethernet port. These phones use a dial-up Internet service to connect to a remote VoIP server and therefore do not require a broadband connection.

Another variation on the hard phone is the Wi-Fi phone. This is an IP phone with a built-in 802.11 wireless transceiver in place of or in addition to an Ethernet port. It connects wirelessly to a Wi-Fi base station (called an access point), which is then connected to the Internet. Like other hard phones, it doesn't have to connect to a PC. Wi-Fi phones are made by many of the same companies that make Ethernet-based IP phones.

Analogue telephone adapters (ATAs)
An ATA allows users to use a regular analogue telephone to make VoIP calls. It has an RJ-11 port (for a regular phone line) into which users can plug an ordinary telephone handset. It also has an Ethernet port by which users can connect it to the local network. The ATA communicates with the VoIP server, using a standard VoIP protocol such as SIP, H.323 or IAX. The ATA converts the analogue signals of the phone to digital data so it can go over the Internet.

The VoIP "box" provided by consumer-level VoIP services such as Vonage and Lingo is an ATA. Another name for an ATA is VoIP router.

Digital telephone adapters (DTAs)
DTAs, also called handset gateways, allow businesses with digital Private Branch Exchange (PBX) handsets to use their existing infrastructure for VoIP calls. An IP PBX — which replaces the PBX itself — integrates with all the legacy handsets already in place throughout the enterprise, saving companies from having to replace all those handsets. Handset gateways are available from Citel and Intel.

VoIP interface cards
VoIP interface cards are expansion cards that go into a computer's PCI slot to add VoIP capabilities. Users can plug several phone lines into a single card, install the software that works with the card, and create a system that can automatically answer and redirect calls and record voice mail messages. Vendors include VoiceTronix and Digium.

VoIP gateways
These devices connect VoIP networks to the PSTN system, allowing calls between VoIP phones and PSTN or mobile phones. Gateways perform compression and decompression of voice transmissions, as well as call routing. VoIP gateways may interface with gatekeepers, softswitches or other external controllers, and can incorporate features such as network management and accounting.

VoIP gateways are also known as media gateways. They are made by many of the same companies listed in the IP phone section, as well as Nortel, SysMaster and Oki Network Technologies.

VoIP PBX
PBX systems perform the same functions as a traditional PBX, including call switching/routing within an organisation. Technically, a PBX system uses a live operator to route calls, whereas PABXs (Private Automatic Branch Exchanges) are modern systems that do so automatically.