Network Border Switching

As acceptance of packet voice technologies continues to rise, service providers are willing to take the next step towards deployment of next generation voice networks. Previously, carriers usually deployed next generation solutions in the core of their networks. Typical implementations were circuit-to-circuit, much like legacy switches, or circuit-to-packet, which enabled carriers to improve both their cost structure and service capability. Today, carriers are finding that they would like to interconnect with others using IP (Internet protocol), not circuits, a shift that introduces both opportunities and challenges.

There are four main areas of opportunities for direct packet-to-packet interface:

• Peering - There is a significant shift in carrier networks toward transport of voice using IP-voice. When two carriers who use IP-voice wish to interconnect (peer) with one another, they can gain significant efficiencies by peering at a IP-voice level, rather than each converting the traffic between IP-voice and circuit voice.

• Enterprise access - Carriers are using IP as the interface of choice for enterprise customers. Since enterprise customers now expect a bundle that includes both voice and IP data, using IP for transport has definite advantages. Enterprise voice can be converted to IP-voice using an enterprise gateway, or may be provided directly as IP-voice from the PBX.

• End user access - There is a growing interest in connecting end users to the carrier voice service through IP. IP-voice is being used to provide voice service over almost any type of broadband connection, including DSL, cable modem, and high-speed fixed IP access. In such circumstances, the customer device can be one of a number of alternatives, including an IP phone, a “soft” phone, or a standard phone attached to an adapter or Integrated Access Device (IAD).

• Application Service Provider (ASP) access - Carriers often implement enhanced services on separate application platforms. Along with the transition to IP-voice, carriers are also beginning a transition in the interface used between these enhanced services and network devices. Instead of the complex SS7-based (AIN) protocols used in legacy networks, carriers are increasingly using IP-based interfaces. This shift increases the opportunity for implementation of enhanced services by ASPs, who use the IP interface to interact with the carrier systems.

The IP interfaces used for the types of connections above are considerably more open to misuse than the circuit interfaces that preceded them. In addition, the increased flexibility of IP introduces the added possibility of incompatibility. NAT devices, firewalls, and session border controllers have been used to solve pieces of the overall problem, but until now, there has not been a single solution that addresses these issues.

Through the IP Multimedia Subsystem (IMS) architecture, the Sonus Network Border Switch allows carriers to take advantage of new opportunities, and avoid the dangers, while maintaining the high standards expected of carrier networks.

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