Geographic and regulatory considerations Internet Protocol (IP) connectivity options Dial plans and call routing Supplementary services Network demarcation Security considerations 102 SIP Trunking Session management, call traffic capacity, bandwidth control, and Quality of Service (QoS) Scalability and high availability SIP trunk monitoring Another key area of consideration includes interworking and interoperability, which is discussed further in Chapter 8, "Interworking." Sample configurations of specific implementation examples to select service providers in the market are provided in Chapter 10, "Deployment Scenarios." Geographic and Regulatory Considerations If your network spans multiple geographic boundaries, continents, or countries, keep in mind both regulatory and distance considerations: Regulatory: Not all countries regard Voice over IP (VoIP) calls in the same way, and although virtually no country regulates what can be deployed inside an enterprise network, several countries regulate to varying degrees what calls can be handed off between an enterprise and a public (service provider) network. Ensure that you be- come familiar with country-specific regulations when deploying SIP trunking, espe- cially if the endpoint (the site where the call originates) and the SIP trunk (where the call enters a public network) are in different regulatory jurisdictions. Distance: A second consideration is sheer distance, with the hairpinned media paths resulting from the centralized SIP trunk model discussed in the Chapter 6. If the remote office originating the call is in California and the central SIP trunk is in New York whereas the PSTN destination of the call is again in California, the media path for this call traverses the North American continent twice, adding latency to the end- to-end call. Adding latency to signaling paths is much less of a concern (it might add marginally to post-dial delay but does not impact voice quality on the active call), but latency of the media path directly affects voice quality a