Written for both voice and networking professionals, this guide overviews how a basic telephony infrastructure is built and explains major concepts concerning voice and data networking, transmission of voice over data, and IP signaling protocols used to internetwork with current telephony systems. Protocols that affect VoIP are covered in detail. Network administrators and software engineers will appreciate the book's review of VoIP basics. This second edition includes new chapters on security, the importance of billing and mediation in a VoIP network, and common types of threats inherent with the interoperation of packet voice environments, public switched telephone networks, and VoIP. Davidson is affiliated with Cisco Systems. Annotation ©2006 Book News, Inc., Portland, OR (booknews.com)