VOIP Gateway

**Admin** Wed Feb 24, 2010 8:37 am

Although they’ve been around for years, VoIP gateways remain something of a mystery. What, exactly, are these devices gateways to? Do they lead the way into a data network, a voice network, telephones, network management or outright confusion? In a way, they actually open the door to all of these areas. That's because VoIP gateways have become a central, yet complex, component in most state-of-the-art VoIP systems.

VoIP gateways act as VoIP network translators and mediators. Perhaps most importantly, they translate calls placed through the public switched telephone network (PSTN) - the "regular" telephone system - into digital data packets that are compatible with an enterprise's VoIP system. VoIP gateways can also help direct VoIP calls to specific users with the assistance of built-in routing tables. Additionally, the units can translate between different VoIP protocols, such as H.323 and SIP, enabling compatibility between various VoIP systems and devices.

Given all of these benefits, it's easy to see why VoIP gateways are highly recommended for virtually any VoIP implementation. Yet this hasn't always been the case. In VoIP's early days, system designers often "VoIP-enabled" switches and routers to handle key gateway tasks. But as VoIP networks grew larger and more sophisticated, and as end users began demanding higher quality and more reliable service, most designers began specifying standalone VoIP gateways for their systems.

Various Vendors
With VoIP technology steadily gaining momentum, VoIP gateway shoppers have an array of products to choose from. Leading VoIP gateway vendors include Cisco Systems, Mediatrix Telecom, Quintum Technologies, Stratus, Welltech Computer and Nortel Networks.

VoIP gateways can be either hardware- or software-based. Hardware-based VoIP gateways - by far the most widely used approach - are available as standalone boxes, chassis cards or modules. Hardware VoIP gateways, while generally most expensive than their software counterparts, are usually preferred because they are viewed as more reliable, provide built-in interfaces and don't consume computer processing power.

In the enterprise market, VoIP gateways come in many different configurations. Buyers can select from products that offer numerous phone, fax machine, PBX and PSTN support capabilities. Additionally, for large enterprises with offices and branch operations spread around the country or world, VoIP gateways provide an effective way to extend and distribute voice communications systems.

At the market's low-end, it's possible to find a basic VoIP gateway, featuring a phone jack, Ethernet router and firewall, for under $200. A device at this price level would likely offer a minimum of three ports: a standard RJ-11 telephone jack and two RJ-45 ports - one for a broadband modem/router and one for a computer or network sharing device. Such a system would be capable of handling the voice needs of a home or small office.

A mid-level VoIP gateway, costing anywhere from $400 to $2,000, offers additional interfaces supporting a wide range of phone system and network devices. These products also include various quality of service (QoS) features, network-thrifty voice compression and built-in security capabilities, such as encryption. The primary selection criteria of these VoIP gateways is the maximum packet throughput and the number of simultaneous phone calls supported. A VoIP gateway buyer needs to know just how much capacity his or her VoIP system needs, and these figures can only be arrived at by a thorough professional analysis.

At the market's high end are Carrier Class VoIP gateways, costing several thousand dollars. Widely used by both telephone carriers and large enterprises, these devices support hundreds or even thousands of channels for advanced voice services, such as interactive voice response (IVR), a technology that allows callers to select an option from a voice menu. Other advanced functions supported by carrier-class VoIP gateways include voice recording, distributed voice announcements and conference calls.