 the benefits will be when transitioned to SIP trunks. Phase II: Determining the Priority of the Project Generally two major reasons exist that you need to consider when transitioning to SIP trunks at an enterprise: cost and features. There are also several secondary reasons that lead enterprises to consider utilizing SIP trunks. These include the lack of availability TDM trunking services from providers or the lack of availability of data center or remote office space to implement TDM trunks. After you determine the primary reason for the consideration of SIP trunks, the next step is to determine how this program can fit within the context of the larger IT transitions and programs that occur. When considering a SIP trunking implementation as a method of cost-savings, you need to understand what the payback period is and that the esti- mates used to determine this payback period are realistic. A successful implementation of SIP trunks can be used as a cost-savings method to help pay for the implementation of other components of a UC solution. This is an important point to stress when considering the implementation of SIP trunks, and a ROI calculation is provided in Chapter 4, "Cost Analysis." The other major reason for implementation of SIP trunks is to access new features that could not be accessed with TDM trunks. An example of a feature that is more widely deployed on SIP trunks than previous trunking methods is video calls. You can imple- ment high-definition video calling on H.323 trunks and TDM trunks; however, the most advanced features, such as Cisco Telepresence, are currently implemented utilizing SIP trunks. Other new features implemented using SIP trunks that should be included when considering the priority of the project include the following: High-fidelity calls utilizing wideband codecs Calls with subject lines that appear in addition to caller ID and caller name Chapter 3: Transitioning to SIP Trunks Multimedia calls that include voice, video, chat, and file exchange Presence indicators across and