NEW DELHI: The telecom regulator on Friday made it mandatory for operators to notify subscribers about their data consumption at regular intervals, following several complaints of overcharging.Service providers must inform consumers after every 10 megabytes of data is used, the Telecom Regulatory Authority of India said while notifying the Telecom Consumers Protection (Eighth Amendment) Regulations, 2015.Subscribers using data services through special tariff vouchers, combo vouchers or add-on packs have to be alerted when they have consumed 50 per cent, 90 per cent and 100 per cent of the data. Alternatively, they should be informed when the data balance in their accounts reaches 500 MB, 100 MB and 10 MB.The regulator made it mandatory for telecom service providers to notify subscribers about the details of 'new' tariffs applicable after the data limit is exhausted, when 90 per cent of the data limit is reached or when the data balance reaches 10 MB. Operators must alert customers about international roaming and caution them to deactivate data services if they don't intend to use them. The service providers have been given time till November 15.The regulator said on Friday it had received several complaints from consumers on charging for data services. "In many cases, the customer knows about it only after the balance is exhausted," the regulator said, explaining why it had issued the instructions.Many subscribers also complained that they were not informed when the data pack had been exhausted or when the quantum of concessional or discounted tariffs in a plan was over. As a result, they were charged a higher tariff for data without their knowledge.