A ruling by India’s high court preventing private companies using customers’ national Aadhaar ID to verify their identities will slow mobile registrations and increase user acquisition costs as much as ten times, The Economic Times (ET) reported.

Operators in the country had used the 12-digit IDs, which are issued to all Indian residents based on their biometric and demographic data, to register new customers. The Aadhaar system was put in place in August 2016

A representative from one operator told ET it will now take five to six days to verify a customer’s personal data by sending an agent to their home, whereas with Aadhaar it took 30 minutes.

Another operator representative said without the system the cost of verifying customers would jump from INR30 ($0.41) to between INR250 and INR300 because data has to be physically verified.

Sources told the newspaper operators will need to voice their concerns with the Department of Telecommunications and call for a meeting with the government.

An estimated 500 million mobile subscribers in India have been verified using Aadhaar, around half the country’s total subs. More than 80 per cent of new customers use the system for verification, ET said.

The Cellular Operators Association of India said it is assessing the implications of the ruling, ET reported.

While the Supreme Court struck down a provision in the Aadhaar act which allowed private organisations to use the digital ID for other purposes, such as verifying identities, it approved the use of the system for public expenses, including government benefits and income tax collection.

The ruling is a major setback for Prime Minister Narendra Modi’s digital India push.