Failover for SMB VoIP Systems

One of the risks of broadband-based IP telephony is that if your Internet connection goes down, for whatever reason, you’ve got no phones—not to mention e-mail, e-commerce, and whatever other Internet based applications you rely on.

An obvious way around this problem is to have more than one WAN link—from more than one provider. That way, should one link go down or become overwhelmed with traffic, another link can pick up the slack—if there’s a way to manage the traffic flow.

That’s exactly the idea behind ClariLink, a new family of WAN link controllers just announced by Ecessa (formerly Astrocom), a veteran provider of network controller devices. ClariLink is especially adapted to the needs of VoIP traffic, in that it is designed with special SIP (def.) application management capabilities.

With ClariLink, SIP traffic can be deployed reliably across multiple WAN and/or service provider networks for redundant link connectivity and automatic real-time failover. The device includes a SIP proxy (def.), SIP registration server, and Network Address Translation (NAT) proxy that allows SIP traffic to be load balanced with failover among multiple WAN links.

“More and more businesses are showing their interest in SIP trunking services, but some concerns around reliability remain,” said Infonetics Research analyst Matthias Machowinski. “With Ecessa’s newest product, SMEs can deploy multiple WAN links, and enjoy high availability, automatic failover and link redundancy, ensuring the continued reliability of their IP network connectivity.”

The ClariLink NAT proxy provides a way to circumvent one of the thornier problems of SMB VoIP adoption: the difficulty of SIP traffic traversing NAT-based firewalls. Since the ClariLink controller functions as the primary NAT device, traversal problems go away—boosting the reliability of the phone system in another important dimension.

While SIP signaling is used for applications other than voice, Ecessa expects that voice will probably be the main driver for its adoption. “A large chunk of customers will be VoIP users who want the reliability and high availability and load balancing and failover, the quality we can provide being integrated with an appliance that does all those things,” said Brad Johnson, lead developer for Ecessa.

“We have beta sites looking to go to VoIP,” said Johnson. “They currently have a single PRI (Primary Rate Interface) line to the PSTN (Public Switched Telephone Network), so if that line goes down they lose their phones. They are very interested in the cost savings by going to VoIP and using a product such as ours.”

The new WAN link controller is aimed at small and midsized customers looking for more effective voice network management and to manage and shape their bandwidth traffic, but Johnson emphasized VoIP isn’t the only usage scenario for ClariLink. For example, it can also handle data, multimedia and interactive initiatives.

The ClariLink line will be available in the third quarter. The company said pricing hasn’t been finalized.

This article was adapted from an article first published on

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