Feature Story

Are SIP-Based Networks Ready for Prime Time?

By Ian Colville

There is no doubt that IP technology has become ubiquitous in modern communications networks. It is a fundamental element for a vast array of business-oriented solutions that help customers manage key processes, like increasing revenue, improving operations, enhancing communications, and controlling costs. Yet, as powerful and commonplace as IP solutions have become, the technology is often based on a best-effort protocol that does not match legacy SS7 technology in terms of reliability – a crucial distinction for business customers.

As a result, businesses, especially ones that are looking to leverage the profound benefits of IP hosted solutions, are taking a serious look at these IP solutions to determine if they are indeed ready for the big time. What they’re finding is a harsh reality: SIP-based services continue to suffer from a lack of network resilience and failover within the IP network. Concepts like five-nines reliability and always-on availability, while commonplace in legacy environments, are not the norm in an IP setting.

Meeting Customer Expectations

The reliability issue can be particularly problematic for many hosted solutions providers as they look to migrate customers to SIP-based solutions. These new customers, which by and large have had positive experiences with legacy networks, fully expect that the SIP-based services will perform in a manner similar to solutions in the legacy SS7-based environment. As a result, they will not tolerate any degradation in quality or reliability from their new solutions. If their experiences are less than optimal, they will in all likelihood revert to the comfort zone that is the SS7 network, and all of the touted benefits of hosted IP solutions will fall on deaf ears.

Enter Dual Redundant SIP Service

Among varying methods to improve the performance of IP-based solutions, there is growing interest in the deployment of a dual-redundant SIP service within the IP network. This capability employs advanced IP signaling gateways to increase the reliability of the SIP-based solution to the level of legacy TDM-based SS7 technology. DRSS signaling gateways operate in a paired configuration with an active server and a standby server that mirrors the active server in real time, similar to the way SS7 signaling nodes are configured.

Communications service providers can then factor in network resilience and service continuity as a core part of their service. In the event of a failure, the redundant operation of the DRSS signaling nodes ensures the system intelligently fails over to the standby server. Calls that are connected at the time of such a failure remain connected — just like in the SS7 world. This creates a self-healing infrastructure, transparent to the user.


While most industry experts and influencers wholeheartedly support the notion that hosted communications services will continue to gain momentum in the marketplace, the challenge lies squarely on the shoulders of providers, which must find a way to improve the reliability of the IP infrastructure to satisfy user expectations. A dual-redundant SIP service is an effective and reliable means for hosted services vendors to improve network performance and ensure the seamless delivery of cloud-based voice, collaboration, contact center and high-demand business and consumer services. IT

Ian Colville (News - Alert) is product manager for Aculab (www.aculab.com).