Gud Day
Well Shadow,we patch E1 cables just to link two different euipment.like we connect M/W PCM cable to BTS cable by patching in Kronea.and the same process we do in integration to reach to BSC from the Source Cell and than from BSC to MSC.No of E1 cables depends on sort of link(PDH/SDH)or more so there is a cabinet in the BSC to patch in Kronea.
Hope u understand.