He said Trai may soon come out with a consultation paper on the subject and invite suggesstions about making it mandatory for operators to provide customers with this option.
"Even there (in per-second tariff plan), they must ensure to bring out clearly all the riders and caveats," Sarma noted.
The Trai chief further said that since the current regulations allow the operators to decide the tariffs on their own, "I cannot say whether the time has come to reconsider this particular clause."
Some of the telecom players in the country have already launched per-second pulse, but such tariff plans are not mandatory and are mostly aimed at expanding their penetration and expanding market share.
Last week, state-run BSNL introduced one paise per second pulse (for local calls) and two paise per second pulse (for STD) in Karnataka, Andhra Pradesh and Orissa.
Private sector Tata Teleservices broke away from the norm by offering users per second pulse on its GSM network — a development the company attributed to its becoming the top operator in terms of user additions in August.
Another operator, Aircel also extended its pay-per second calling plan from Kolkata and Orissa to Uttar Pradesh last week.