 not as easy as deploying TDM trunks. People have worked with TDM trunks for many years; and it is a mature technology. You can find enough experts to install and troubleshoot your TDM trunks, but for SIP trunks, you might not easily find SIP trunk experts. Over time, though, it will be an easier task for professionals. Because few people are trained in this domain, you might need to hire a consultant to help you design and run your network. This will likely cost more than installing a TDM trunk. In the SMB market, Cisco is trying to alleviate the cost associated with this expertise by doing SIP Trunk interoperability testing with the larger service providers and document- ing this in various tools and application notes to overcome the learning-curve hurdle. Other Areas of Costs and Savings We have already discussed the major areas of cost to deploy the SIP trunk. In this sec- tion, we discuss where you might need to keep some budget money, and we talk about ways to save money. You might need to maintain some backup links to keep your communication up and run- ning during the failure of WAN or SIP trunks. Based on the size of the users, you can put some FXO or T1 ports connected to PSTN to support during failover. Some companies use separate analog lines to connect their modem or FAX machine. Although these cost a small amount of money, it is better to account for them. A big benefit of the new agreement comes with disaster recovery because IP trunks enable automated switching around locations damaged in a storm or other disasters. Before SIP trunks, reconfiguration for a disaster would have been done manually, result- ing in lost time. Although a SIP trunk takes away complexity, it also enables easier scalability. If you need to expand your operation, you need to order a new interface card for T1s/T3s; you need to get local loop (a trunk roll is involved); and you have to wait for provisioning the entire Chapter 4: Cost Analysis 55 thing. To accomplish the expansion, you need to plan and execute ahead of time. Y