New Delhi: India will introduce mobile number portability (MNP) on 31 December, a move that could further intensify the stiff competition in the world’s fastest growing wireless market and push call chargeslower.

MNP, which allows users to retain their number even if they switch operators, will be introduced in two phases, the country’s telecom regulator said, first in the metro cities and the so-called category A telecom zones, and in other areas by 20 March.

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The move will help in “increasing competition between the service providers and acts as a catalyst for the service providers to improve their quality of service”, the Telecom Regulatory Authority of India said on its website.

The regulator also notified certain charges associated with MNP and said switching charges for users must not exceed Rs19.

Four new firms, including ventures of international telecom operators Telenor Group, Etisalat and Batelco, are set to start services in India this year and MNP would make it easy for them to attract existing users of such services.

Separately, Bharti Airtel Ltd, the country’s largest phone company, launched yet another new billing plan on Friday, slashing mobile roaming rates by nearly 60% and signalling a tariff war was far from over.

The price war has raised concerns about telecom firms’ profitability.