 contain the ineffective attempts our wireless telephone system is experiencing. The clue that tells us which kind of air-interface congestion is blocking calls is the distribution of the ineffective attempts: If ineffective attempts are distributed fairly evenly throughout the sector or are distrib- uted as the overall traffic is distributed, then we have a green area as described above. If ineffective attempts are concentrated in specific areas and happen whether or not the sector is busy, then we have a red area as described above. If the ineffective attempts concentrate in some areas and seem to spread out to a larger area as the traffic load increases, then we have a yellow area. From these clues, we can deduce what radio conditions are causing our CDMA carrier to block calls. 40.3 Lost-Call Complaints Lost calls are a major embarrassment to a wireless service provider. When subscribers are cut off in the middle of their calls, they are reminded that they are not using the reliable landline telephone network. Lost calls create the impression for subscribers that this is still a toy telephone system, not a medium for serious or professional com- munication. It is usually best to block calls rather than to lose them in progress. The usual reason for a lost call is a good radio signal becoming bad. Unless a piece of equipment actually fails, this is the only reason a call should ever stop once it has started. Radio signals can go from strong to weak because a user terminal moves from a high radio path gain area to low path gain. We think of a subscriber driving into a valley or walking into a building. But CDMA can lose calls by running out of capacity as well. When the antenna face serves a call over the limit, the CDMA carrier becomes overloaded. It is not necessar- ily the new call, the extra call, that is going to be lost. Even if our design is smart enough not to take on new calls that overload the CDMA carrier, a handoff can come along and add to the CDMA carrier load. Turning down a handoff request and l