A VoIP and convergence history lesson, part two

In part one of this history lesson, we noted that by “Y2K”, VoIP was alive and well in the long distance carrier market, beginning its journey into replacing legacy PBX voice systems with an IP-PBX. Supplemented by Session Initiation Protocol (SIP), the IP PBX brought new capabilities to enterprise voice services including features such as the ability to integrate directories, softphones, and presence management.

The session border controller (SBC) was born, initially to offer voice carriers a meet point for VoIP calls as a means to set up and tear down calls. The SBC soon evolved into a gateway device to allow interoperability between calls that used different signaling protocols that included SIP, H.323, and MGCP. SBCs eventually added performance monitoring and management, also helping to solve VoIP security concerns with techniques such as stateful packet inspection. As enterprises added IP communications systems, the SBC found its way into corporate networks as a useful interface between the enterprise and carrier VoIP and IP networks.

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