lding and all its contents. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Switching Capacity Capacity and Quality Principles MSC has a direct connection to an interexchange carrier for long-distance service, then the digits have to be analyzed for long-distance routing. Finally, once all the decisions are made, the processor has to assign resources to switch the call. Each voice-call termination uses processor resources for call processing and for lo- cating the user terminal. The MSC has to interpret the dialed digits, communicate with the HLR and base stations to pinpoint the MSC and base station serving the user ter- minal, and set up the call. Roamers use call-processing resources at their home and serving MSCs with some unavoidable duplication of effort. Subscriber features use switch resources. Incoming call-waiting calls require the processor to notify the subscriber, to detect flashes, and to do the appropriate switch- ing. Similarly, three-way calls keep the processor busy managing the extra connection, at least as much work as a new mobile origination. Data calls are not terribly different from voice calls as far as the MSC processor is concerned. It has to establish an Internet Protocol (IP) link for the subscriber and di- rect the packet-switching components to send their packets into the landline data net- work. While the packets may need some processing of their own, this should be inde- pendent of the MSC main processor. Voice-call releases use call-processing resources as well. Resources allocated have to be freed, and there is communication with the base station, the HLR, and perhaps the visitor location register (VLR). In capacity planning, we can consider the call release activity as part of the call origination and termination workload because every call has to end sometime. Accounting and statistics have to be maintain