One of the critical elements of a SIP trunking installation is the PBX (News - Alert). A PBX is the central switching system for phone calls, video calls, e-mail, fax, instant messaging, conferencing solutions, SMS, and mobile telephony within a business. The PBX handles internal traffic between stations and acts as a gatekeeper to the outside world.

A PBX offers shared access to limited resources. Rather than having a separate line for each phone, a PBX allows a business to share a smaller pool of lines across the entire business, saving money. It serves as the backbone of your business, providing call routing, call transfer, voice messaging, and more.

An IP PBX offers even more advantages. For employees it means mobility, with access to voicemail, SMS, presence, and more. An IP PBX also affords more communications options – fax, video, video surveillance – giving you more products to offer customers. It also means you have an interconnected business with one platform for all communications, and boosts productivity with videoconferencing and other real-time communications capabilities.

(Grandstream gave an informative presentation on the benefits of PBXs at the recent SIP Trunking, UC and WebRTC Seminars at ITEXPO (News - Alert), available online on the Ingate Website).

One of the problems for end users and SIP trunking service providers is interoperability between the service provider’s telephony switches and the PBX at the customer premises. To be truly effective – and secure – every customer’s IP PBX must work seamlessly with the SIP trunk service. Achieving certification with every vendor is a costly and time-consuming process, but very necessary.

The solution: utilizing an enterprise session border controller at the edge of the network, which serves as a normalization engine – or universal adapter – connecting the PBX to the SIP trunk and supporting requirements for authentication and signaling. With a single E-SBC, the carrier is instantly, truly interoperable with the IP PBX, offering its customers the reliability of a proven interop solution.

Steven Johnson (News - Alert) is president of Ingate Systems (www.ingate.com).