Leading telecom operators Aircel, Vodafone and Idea are using call drop masking technology or RLT incorrectly in Mumbai, the Telecom Regulatory Authority of India said on Tuesday.
"Most of the operators have focused on network improvement. However, usage of RLT (ie time-out period for releasing the call) by Aircel, Vodafone and Idea is incorrect and needs to be addressed immediately," Trai said in its Mumbai drive test report.
With the use of RLT, a call remains connected even if a consumer moves to a poor network coverage area, for which he is billed.
However, industry body Cellular Operators' Association of India has denied the allegation, stating that the so called 'call drop masking technology', is actually a network parameter called Radio Link Time Out (RLT), which is a part of the GSM standards and is used globally.
It said that RLT is just one of the parameters, which decides for how long the call should be sustained if the signal quality drops below a certain threshold.
Trai has found RLT level of 40 units being used by most of the telecom operators but some companies have been using it beyond their peers in a city.
"Such use will delay a dropped call by not providing any audio to the consumer and forcing him to disconnect, while charging him for time the call was inaudible. Thus, the reduction in CDR (call data record) is not an accurate reflection of improved customer experience," Trai said.
Vodafone was found using higher RLT value than its peers in 97 per cent of cell sites, Idea Cellular 80 per cent and Aircel around 64 per cent of cell sites. Tata Teleservices was found using higher RLT value in 23 per cent of cell sites in Mumbai.
Vodafone has been found using higher RLT value in Delhi and Hyderabad and Aircel in Delhi and Chandigarh.
"Most of the operators are not meeting the Call Drop Rate benchmark of less than or equal to 2 per cent except Airtel 2G & 3G and Vodafone 2G," Trai said.
"MTNL 2G & 3G and Tata CDMA has performed very poor" in Mumbai drive test, the regulator said. "Aircel 2G, Reliance 2G, Tata 2G and Vodafone 3G will need to focus on their Call Drop Rate reduction while Idea 2G, all CDMA operators and specially MTNL 2G & 3G need to improve across all parameters, in order to offer acceptable levels of service," Trai said.
The drive test was conducted randomly over a stretch of about 580 kilometers between 10-13 May.