A method, effected by a processor of a component of an asynchronous wireless communication system or by a workstation of a dedicated system outside of the asynchronous wireless communication system, of determining the differences dTb(i,j) between base station timing offsets Tb(i), Tb(j) for pairs of base stations B(i), B(j) in the asynchronous wireless communication system, comprising: obtaining an initial set of estimates for the differences dTb(i,j) derived from an analysis of calls from a past time interval, and a set of measurements of a timing of signals received by one or more wireless communication units, using measurements Tm(i), Tm(j) of the timing of signals received by a wireless communication unit, of the one or more wireless communication units, from a pair of base stations B(i), B(j) to derive a first location estimate of the wireless communication unit, estimating a difference dTpath(i,j) in first path lengths for signals received by the wireless communication unit from the pair of base stations B(i), B(j), estimating differences dTpath(i,j) in second path lengths for signals received by the wireless communication unit from other pairs of base stations, and/or by other wireless communication units, estimating a second location estimate of the wireless communication unit on the basis of the dTpath(i,j) estimates, revising the dTpath(i,j) estimates using the second location estimate, using the revised dTpath(i,j) estimates to produce a revised set of differences dTb(i,j), deriving a first confidence score for the first location estimate and a second confidence score for the second location estimate, and using the revised set of differences dTb(i,j), weighted by the first and second confidence scores, to make changes to the initial set of estimates of differences dTb(i,j). obtaining an initial set of estimates for the differences dTb(i,j) derived from an analysis of calls from a past time interval, and a set of measurements of a timing of signals received by one or more wireless communication units, using measurements Tm(i), Tm(j) of the timing of signals received by a wireless communication unit, of the one or more wireless communication units, from a pair of base stations B(i), B(j) to derive a first location estimate of the wireless communication unit, estimating a difference dTpath(i,j) in first path lengths for signals received by the wireless communication unit from the pair of base stations B(i), B(j), estimating differences dTpath(i,j) in second path lengths for signals received by the wireless communication unit from other pairs of base stations, and/or by other wireless communication units, estimating a second location estimate of the wireless communication unit on the basis of the dTpath(i,j) estimates, revising the dTpath(i,j) estimates using the second location estimate, using the revised dTpath(i,j) estimates to produce a revised set of differences dTb(i,j), deriving a first confidence score for the first location estimate and a second confidence score for the second location estimate, and using the revised set of differences dTb(i,j), weighted by the first and second confidence scores, to make changes to the initial set of estimates of differences dTb(i,j).