These issues should be taken into account when planning and managing the bound- aries between service providers. 36.2 Call Processing The connection between call processing and signaling messages is based on subscriber activity, as described in Sec. 25.3. The capacity requirements for call processing and signaling messages are not correlated with borders zones or the locations of sub- scribers, unlike the requirements for handoffs and roaming. Call processing is well un- derstood and happens everywhere in the wireless telephone system. Every time a user terminal is turned on, it registers with the nearest base station, and the serving MSC contacts the HLR. When the user terminal moves from one MSC region to another, it registers again and updates its database record in the HLR. In ad- dition, base stations periodically will check to see if registered user terminals are still within range, adding a bit more demand to the signaling load. The registration load on 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. Signaling Capacity Planning Planning for CDMA Capacity the signaling network is the number of user terminals being turned on or off plus a bit extra for confirmation of registration. The rest of the call-processing signaling workload is from actual call activity. Every time a call starts or stops, messages are sent to the HLR. Every time a subscriber uses call waiting or three-way calling, messages are sent to the HLR. We should have good forecasts of the amount of call processing we expect in a wireless telephone system. For voice calls, we know the average call duration, and we have forecasts of the total call demand. We needed those forecasts to decide how many base stations and MSCs to build and how much backhaul to provide. Data service also uses call processing to set up sessions and to end them, but we do not have as good a feel fo