iest MSC-to-MSC routes are going to benefit from dedicated facilities for incoming roamer calls. 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. MSC Transport Planning MSC Transport Planning As the MSC count increases, the inter-MSC roamer termination count also will in- crease. More specifically, the fraction of incoming calls at each MSC that are roamer terminations at other MSCs will increase. As a system has more MSCs, the MSC re- gions get smaller, so the likelihood becomes greater than a subscriber is in a neighbor- ing MSC region when a call comes in. The time-of-day picture is also very important for this kind of analysis. It is not the peak-hour traffic load that matters for cost savings but the amount of inter-MSC traf- fic that is sustained over enough hours of the day to justify the expense of a dedicated link. The roamer termination traffic can be combined with the mobile-to-mobile traffic (see below) in taking advantage of the cost-reduction opportunity of dedicated transport. The handoff links, however, are separate. 37.1.3 Mobile-to-mobile calls Just as in terminating roamer calls above, sending mobile-to-mobile calls through ded- icated transport instead of the PSTN is an opportunity for cost savings. We can run these calls through the PSTN on a call-by-call basis, or we can lease our own transport for them. In Sec. 26.3.2 we discussed the criteria for saving cost with dedicated inter- MSC transport. The first step in determining where to save cost in mobile-to-mobile calls with dedi- cated inter-MSC transport is figuring out which MSC pairs would benefit. The best candidates have a lot of mobile-to-mobile traffic between them distributed fairly evenly throughout the day, so a leased DS-1 or E-1 link would be kept fairly busy for several hours per day. The best candidates for inter-MSC transport, for roamer terminations as w