FP, which is examined in subsequent chapters can be considered and explored. Chapter 4 Cost Analysis This chapter covers the following topics: Capital costs Monthly recurring costs Cost of usage Cost of security Cost of expertise/knowledge Other areas of costs and savings This chapter focuses on the cost structure of deploying the Session Initiation Protocol (SIP) trunks. This is also one of the major criteria to select the SIP trunk service provider. Different service providers offer different cost models. You should consider some com- mon criteria during your cost analysis. SIP is the protocol for creating, modifying, and terminating sessions (voice, IM, conference call, and SO on) with one or more participants. It is widely used as the signaling protocol for Voice over IP (VoIP) calling and is widely thought of as the standard. So when we talk about SIP trunks, it is similar to a phone line used for making and receiving phone calls. SIP trunking enables the convergence of voice and data on one circuit. In some cases, you might want to keep your voice network and data network separate (more on this in Chapter 7, "Design and Implementation Considerations"). However, the same physical wire might be used to connect to your service provider. Cost structure also depends on your deployment architecture (that is, centralized, distributed, or hybrid). Following are some leading reasons why people are switching to SIP trunking: Increases the availability of the service from multiple services providers. You are no longer dependent on your local PRI providers. 46 SIP Trunking Increase the redundancy of the services; for example, if you have contact centers in different locations and want to move one of them to another location. It is easier to do migration, load balancing, capacity increment, and SO on. Allows rich media such as wideband audio, video, presence, telepresence, and SO on. Reduces or eliminates the costs associated with the purchase of T1 and analog trunk cards. Reduces toll charges for long-distance, interna