maller than the old MSC regions, and doing a traffic engineering exercise. For inter-MSC transport, we need to figure out how much handoff activity we expect and how much mobile-to-mobile and roamer-termination traffic we expect as well. These calculations are the same as those in Sec. 37.1. The inter-MSC transport for handoffs must be adequate or else inter-MSC handoffs will fail, and the CDMA air in- terface will lose capacity as a result. The mobile-to-mobile and roamer-termination links can overflow to the PSTN. This may cost more money, but it will not lose system capacity. We can take the combined voice traffic for the base stations in the new MSC area to get the requirement for how much circuit-switching equipment and speech-coding equipment to use. Similarly, we can total the packet-switching requirements of the base stations to get the requirement for the packet-data-switching capacity. The mix of services can change over time. When we are buying equipment for a new switch, we should be prepared for our subscriber community to change its preferences. Third-generation (3G) services may increase dramatically over time, and we should be prepared for this. We also should be prepared for a system that has a steadily growing voice demand, as cellular telephone services has had for two decades. The decision to add a new MSC to a wireless telephone system also should include a complete description of the equipment required so that MSC can serve its traffic. As we continue to expand MSCs, both old and new, we will find ourselves upgrading equipment, as we described in Sec. 43.1. A new MSC will have all new equipment, and that equip- ment, has to work with our existing base stations. It also has to communicate over inter- MSC links with the other MSCs that may not yet have all the latest equipment. We also must make sure that the systems that monitor and operate a new MSC are compatible with the new equipment. We have to remember that a new MSC needs electrical power and environmental support to operate and that i