India introduced mobile number portability (MNP) after postponing the introduction of the service three times because operators were not ready with the infrastructure to offer the service.

The service is however being rolled out Thursday, but only in Haryana state, with a plan for phased migration in all other service areas still to be worked out. The detailed program for the entire country will be announced separately, the Ministry of Communications and Information Technology said.

Number portability allows mobile subscribers to retain their phone numbers even if they change service providers. India had over 670 million mobile subscribers at the end of August, according to the Telecom Regulatory Authority of India (TRAI).

Under guidelines proposed last year by TRAI, mobile users will be allowed to use the same mobile number even if providers use different mobile technologies like CDMA (code division multiple access) or GSM (Global System for Mobile Communications).

The MNP service was to have been originally introduced in the country in December last year.

Mobile phone customers in the Haryana service area will have the choice of selecting their telecom service operator without changing their number, provided a minimum period of 90 days has elapsed after subscription to the mobile service of the current service provider, the communications ministry said.

MNP is expected to increase competition in the mobile telephony market in India as customers will have the choice to shift operators, if they are not happy with the quality of service or the tariff, without having to give up their mobile numbers. Indian operators are locked in a price war that has pushed down their margins.

Apart from an initial surge in customers shifting to other service providers, the MNP will not have a significant impact on the market, some analysts said.