 phase. Determining where to start might depend on the information provided by your cost/benefit analysis. The contact center tends to have the most complex call flows to accommodate, but the contact center also tends to be an easier area to cost-justify a change such as SIP trunking. Chapter 11: Deployment Steps and Best Practices 247 When rolling out a SIP trunk production service, a common call pattern to start with is outbound long distance and international calls. The reason for starting here is that it is often easy to cost-justify. Also, the more thorny issues, such as Direct Inward Dial (DID) porting for inbound calls, can be delayed until a later phase allowing for more time to work through potential issues. Another common approach is to start with geographic sites. For example, choose a cor- porate user community at a campus site and handle all its calls with SIP trunking while other sites continue to use traditional TDM trunks. This simplifies working through geo- graphical differences between SIP trunk providers and handling emergency calls. (They're all in one location.) It also limits the number of DIDs that need to be ported before pro- duction service can start. In summary, the most common user communities for first-phase production roll-out tend to be one of the following: Contact center A specific call type, such as outbound long distance calls A single site or a small collection of sites in a specific geographic area Define the User Community to Pilot After you determine the user community to target for the first phase of production roll- out, it is time to focus on the call flows and patterns to test during the pilot phase. Ensure all the call types and patterns important to the chosen user community are ade- quately exercised and tested during the pilot phase. The pilot should not involve porting of any DIDs or changing toll-free contact center numbers. Rather, parallel services should be installed during the pilot and the call pat- terns over these "non-production" numbers tested before the 