Abstract: A method for identification of an instable network operator service (NOS) plan having one or more mobile users. Instable NOS plans are determined by first determining a heterogeneity constant for each of a plurality of NOS plans. Based at least in part on the constant, the NOS plans are classified among different categories, wherein at least one category identifies an instable NOS plan. For each of the mobile users subscribed to at least one of the instable NOS plan category, determining a best NOS plan from amongst the plurality of NOS plans and a sample network operator service plan based at least in part on a spending behavior of the respective ones of the mobile users. Identifying, the instable NOS plan from amongst the plurality of NOS plans in which maximum number of mobile users correspond to the sample NOS plan as the correspondingly determined best NOS plan.