This article originally appeared in the August 2010 issue of INTERNET TELEPHONY.
Enterprise media gateways have matured over the years from simple toll bypass devices that enabled cheap long-distance calling to elements that enable a wide variety of solutions within hybrid network infrastructures. One of these solutions is SIP trunking.
SIP trunking is a service offered by ITSPs allowing the extension of VoIP connectivity beyond the enterprise and, in parallel, to the data connectivity requirements. It’s essentially a concurrent call routed over the IP backbone of the ITSP. With this converged voice and data service, SIP trunks offer huge costs savings for the enterprise, eliminating the need for PSTN lines and delivering a fast ROI for the switchover. Enterprises can order call paths based on needs, and these can be added or removed easily as circumstances change.
Moving to SIP trunks requires connecting the internal network and PBX (News - Alert) to the SIP trunk, using a SIP-aware border element. Sounds straightforward, doesn’t it? In reality, a few factors complicate the situation. First, the majority of enterprises’ premises don’t have SIP-enabled PBXs: on-premises PBXs are still mostly legacy TDM PBXs. For these, a gateway function is required to convert the SIP trunk messages to TDM messages that are recognized by the PBX. Second, for premises-based PBXs that support a SIP interface, there are often interoperability issues with the SIP trunk due to varying implementations of the SIP specification. For these, again, a gateway function is required to perform the SIP-to-SIP mediation. Third, for situations in which the SIP trunk can communicate directly with the on-premises equipment, it’s usually desirable to have a demarcation point between the enterprise network and the service provider’s network.
Dialogic (News - Alert) is developing the Dialogic BorderNet 500 Gateway, which will enable the connection of virtually any type of network trunk, (PSTN trunk or SIP trunk), with virtually any premises- based PBX ( legacy TDM, hybrid or IP). The BorderNet 500 Gateway (News - Alert) also will provide the required security functions to establish a demarcation point between the enterprise network edge and the service provider network. A field trial started in July, with general availability slated for the third quarter of this year.
Vince Connors (News - Alert) is product line manager for gateway products at Dialogic Corp.
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Edited by Stefania Viscusi
