tional, and local access calls. Reduces or eliminates the costs of the ongoing support and maintenance costs of those trunk cards. Reduces the recurring monthly costs of separate voice and data circuits (some dedi- cated to voice, some to data). Eliminates the over-subscription of voice; for example, a traditional PRI circuit has 23 useable voice channels that might be more than a small business requires. SIP trunking is available on a per channel/port basis. Affordable Direct Inward Dials (DID) that enable each employee to have his own phone line. Supports multiple forms of communication including video and instant messaging enabling for greater levels of user presence. Enables for single-channel orders, which increase the flexibility and ease of adding, subtracting, or changing a line. Enables remote users to have a local telephone number. Protects your investment. With the proliferation of Unified Communications (UC) everything moves toward Internet Protocol (IP). Deploying SIP trunking is just one step toward that direction. You don't need to deal with the telephone company, its extraordinarily long lead times, poor customer service, and lack of flexibility and responsiveness. These are some of the criteria why customers are moving toward SIP trunking. But this might not always be the case. Different customers might have other reasons to use SIP trunks. Let's look at the costs in more detail. Primarily, two kinds of cost involvement are in a SIP trunking solution: capital costs and recurring costs. We look into each cost structure for our solution. Capital Costs You might need to make a one-time capital investment just to acquire the service. In a broad sense, this is all about your equipment cost and the installation of that equipment and services. Chapter 4: Cost Analysis 47 Cost of Installation The cost of installing a SIP trunk can vary depending on the following factors: Installation of physical connectivity Installation of Customer Premise Equipment (CPE) Installation and configuration of Session Border