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The company's RN appliance would sit in front of two Asterisk servers and handle incoming IP telephony traffic from IP phones and other endpoints by emulating SIP registration connections for the servers. The device also monitors the computer "health" of the two Asterisk servers, checking online status and measuring processor load and network availability. If one Asterisk box fails or becomes overloaded, the RN appliance shifts requests to the back-up server.
Asterisk is an open-source IP PBX software package that runs on Linux, BSD and MacOS. The software provides standard PBX phone system features such as call hold, transfer, multiple-line appearances on phones, directories, conferencing, interactive voice response, call queuing and other features. It uses SIP as its base call-control protocol and supports H.323, as well as QSIG, allowing an Asterisk box to interface with legacy TDM-based phone systems and networks. Asterisk is available as a free download, and is also sold as a commercial product by Digium.
The RN appliance provides a single outward-facing IP address for connecting devices, which allows administrators to take one of the servers off line for maintenance or upgrades without interrupting IP telephony services.
The RN series includes the RN300, RN20, RN40 and RN41, which provide various scaling levels for call handling and failover services. Other services the RN boxes provide for Asterisk servers include bandwidth management, VPN termination, call accounting and LAN switching. The RN300 has three 10/100Mbps ports and can handle 24,000 concurrent sessions with 100Mbps of firewall throughput.
The RN20, RN40, and RN41 can do 256,000 concurrent sessions. With 12 ports of 10/100Mbps Ethernet, the RN20's firewall performance is 500Mbps, while the RN40 and RN41 can process 1Gbps of firewall traffic. The RN40 has 12 triple-speed Ethernet ports (10/100/1000Mbps), and the RN41 has 10 SFP ports for copper or fiber port modules.
The devices range from $600 to $17,300 and are available now.