Like other emerging technologies, enterprise VoIP comes with its own set of buzzwords. These often cryptic terms can be confusing to newcomers and tend to make the technology sound more complex and formidable than it really is.

Here's a quick rundown of some of the common terms you'll see when reading about enterprise VoIP:

Firewall: A set of related programs, usually located at the network's gateway, that protects a private network's resources from external users.

Gateway:
A network interface that converts calls in real time from a public-switched telephone network (PSTN) to an IP network.

H.323: An international standard for real-time voice, video and data communication over packet-based networks, including the Internet.

IP: Internet protocol. The network layer protocol in the TCP/IP communications protocol suite that forms the foundation of the Internet and intranets.

IP PBX: Private Branch Exchange. An enterprise telephone switching system that interconnects telephone extensions to each other as well as to the public-switched telephone network (PSTN).

Packet:
A bundle of binary data sent over a network.

PSTN: Public-Switched Telephone Network. The traditional phone network.

QoS: Quality of service. The ability of a network (including applications, hosts, and infrastructure devices) to deliver traffic with minimum delay and maximum availability.

VoIP: Voice over Internet Protocol. The a general term for the family of technologies that use the Internet Protocol's packet-switched connections to exchange voice, fax, and other forms of communication that have traditionally been carried over the PSTN.

SIP: Session Initiation Protocol. A protocol that provides telephony services similar to H.323, but is less complex and requires fewer resources.

Softswitch:
A programmable network switch that can process signaling for all types of packet protocols, including IP.

VPN: Virtual Private Network. Often used by enterprises to create WANs that cover large geographic areas, VPNs let IP packets travel securely over a public IP network by encrypting all traffic from one network to another.

WAN: A network that covers a wide geographic region, such as a state or country.