redial data may be especially significant by itself it is a direct and instant indication of a network problem when the redial data is localized as shown in fig1 a cellular landscape problem is a likely cause similarly revealing are failed calls i e calls that fail to set up fig1 shows call set up failures as a percent of calls again plotted geographically using data from separate towers here again tower number 7 shows a network malfunction identified in geographical terms an important aspect of the invention is in understanding the value of the data in the context of locating and remedying blind spots in the cellular landscape data like that described in connection with fig1 11 is routinely collected by network oa amp m operations administration and maintenence systems accordingly it is important to analyze the data with a methodology that reveals blind spot defects in the cellular landscape that methodology begins with separating data for cellular calls from land line calls the separation may involve simply suitably selecting the data source for example data from cellular system towers is inherently separating in this context as described above it also is intrinsically sorted by geography for some embodiments of the invention it is useful to separate moving cellular calls from stationary cellular calls the most helpful kind of data for the purposes of the invention is data from a cellular call that terminates while the caller is moving that provides the most likely source of calls terminated as a result of blind spots moreover it allows the.