The regulator Trai has written a letter to various telecom operators seeking information about reasons for the recent tariff hike and measures adopted for communicating the increase to consumers, among other issues.

Trai has written a letter to various operators seeking their responses on issue related to recent upward tariff hike, Minister of State for Communications and IT Milind Deora informed Rajya Sabha.

Further, Trai has asked that whether operators were aware that other service providers had also increased or were planning to increase tariffs during the same period.

"As per Trai, the hike in tariff effected was not across all tariffs plans and for all types of calls. The hike was mainly in respect of promotional and limited period offers, while the charges in the base tariff plans of subscribers remained unchanged. In many cases the hike effected was for on-network calls and the charges for off-network calls remained unchanged," Deora said.

Recently, leading telecom service providers, including Bharti Airtel, Idea Cellular, Vodafone and Reliance Communications had raised tariffs for their services by about 20 per cent in most operating circles.

Most of the companies had cited inflationary pressure in the country as being responsible for the tariff hike.