Foreword

Cisco IOS routers have shipped with voice interface cards since 1997, and after this capability was available the term voice gateway became part of the VoIP vernacular, seemingly overnight. The voice interfaces allowed routers to provide a critical interconnectivity link between the traditional data IP networks and the traditional voice (PSTN, PBXs, and key systems) networks. With this technology, the industry widely built toll bypass networks during the late 1990s: Enterprises connected their PBXs at different sites with VoIP “trunks” instead of with TIE lines or the PSTN, and service providers leveraged IP backbone networks to offer calling-card services and cut-rate long-distance and international calling.

VoIP did not fascinate the ...

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