Bharti airtel is on top when it comes to subscriber complaints related to billing, metering and tariff-related issues and activation of value-added services without customer consent.

In the last three years, Trai received as many as 3,571 complaints from Bharti airtel subscribers, 2,151 from Reliance customers and 1,896 from Vodafone Essar''s clientele.

In all three years -- 2008-09, 2009-10 and 2010-11 (up to December 2010) -- the maximum complaints were against Bharti airtel.

Tata Docomo and Idea Cellular customers seemed to be the least dissatisfied, with 1,239 and 925 complaints, respectively, lodged against them.

The Telecom Regulatory Authority of India (Trai) has been receiving complaints against telecom service providers with respect to various problems, including billing, metering and tariff-related issues, Minister of State for Communication and IT Sachin Pilot said in a written reply to the Lok Sabha.

Trai has forwarded these complaints to the concerned service providers for necessary action.

The regulator has notified the Telecom Consumers Protection and Redressal of Grievences Regulations, 2007, which make it mandatory for every service provider to establish a three-tier system consisting of a call centre, nodal officer and an appellate authority for redressal of the grievances of telecom consumers, the minister said.

Trai has issued a consultation paper seeking views from all concerned stakeholders in order to improve the effectiveness of the grievance redressal system and to protect the interest of consumers in the telecom sector.

Pilot also informed that a telecom operator can offer at any given time a maximum of 25 tariff plans in a service area and this is applicable on all segments of services and also for both post-paid and pre-paid subscribers.