Idea Cellular, Vodafone and Bharti Airtel have gained maximum out of mobile number portability (MNP) service as per the data released till March 31, 2012.

Idea Cellular with 9,297,896 port in and 5,974,318 port-out requests has emerged as top gainer with a net addition of 3.32 million customers, revealed telecom minister Kapil Sibal in a written reply in the Lok Sabha. 

Idea was followed with Vodafone and Bharti Airtel with a net addition of 2.89 million and 1.2 million subscribers respectively.

While port in and out requests for Vodafone are 11,040,863 and 81,50,730 respectively, the same for Bharti Airtel stood at 1,08,27,376 and 9,613,630 respectively, he added.

Sibal also said that complaints against some companies including Bharti Airtel, Idea Cellular and Vodafone have been received by the Telecom Regulatory Authority of India (TRAI) and Telecom Enforcement Resource and Monitoring (TERM) Cells for rejecting MNP requests.

A total of 26,325 complaints have been received so far.

"Based on the complaints received, information was sought from the service providers on the MNP rejections from time to time and coordination meetings were held to resolve the complaints," Sibal said.

"Wherever violations were observed in respect of compliance of MNP regulations/directions, showcause notices were issued to the concerned service providers. So far showcause notices have been issued to Bharti Airtel, Idea Cellular, Loop, Reliance and Vodafone," he added.