 If this middle-stage switch is now removed from the Clos network, "m" is reduced by 1, and we are left with a smaller Clos network.The process then repeats itself until "m" = 1, and every call is assigned to a middle-stage switch.Real telephone switching systems are rarely strict-sense nonblocking for reasons of cost, and they have a small probability of blocking, which may be evaluated by the Lee or Jacobaeus approximations, assuming no rearrangements of existing calls.