Telecom regulator TRAI may have pulled up mobile operators for poor call quality, but a survey commissioned by it has found that more than 90 per cent of subscribers are satisfied with quality of network availability and call drops were few and far between.

According to the audit survey carried out by an independent agency for TRAI, Shyam-Sistema, which offers mobile services under brand name MTS, has the highest number of satisfied subscribers at 96.4 per cent in terms of network availability.

But Shyam-Sistema being a new player is counted among the smallest of operators.

The TRAI statement also also did not give out the size sampled for the survey.

The list puts Tata CDMA as having the second highest number of satisfied customers with 95.3 per cent users expressing happiness, while state-owned BSNL with nearly 100 million users finished at the bottom with a score of 91.9 per cent.

TRAI's benchmark is more than 90 per cent and all operators -- Airtel, Vodafone, Tata CDMA, Idea, BSNL, RCom and MTS are above the benchmark.

For another important parameters of quality of services, the regulator said all mobile operators had less than two per cent (TRAI's benchmark) rate of call drop.

Surprisingly, BSNL was found lacking in most of the parameters vis-a-vis private operators.

In metering and billing, Airtel has topped the list with 95 per cent of subscribers expressing satisfaction with billing performance in the post-paid segment. In these parameters, RCom (CDMA) has only 83.2 per cent satisfied subscribers against TRAI's benchmark of over 95 per cent.

The survey was done for the period July-December 2009, TRAI said in a statement.

Similarly in case of basic wireline telecom services, TRAI said private operators -- Airtel, RCom and TTSL have 100 per cent satisfied customers in terms of network availability while BSNL's score is 75 per cent against regulator's benchmark of more than 90 per cent.

TRAI, however, found that service providers need to take effective steps for grievance Redressal mechanism as the awareness of subscribers was found at low levels in all types of telecom services -- Basic, Cellular and Broadband.