I went to a near by prepaid card and mobile peripheral reseller few months back. Out of curiosity asked him a question about which mobile connection sells faster. He said "TATA DOCOMO is the fast mover, all 500 connection cards of his quota soled out in 2 Hrs and waiting for next dispatch, If you want a new connection book in advance with RS 100 payment." And to my question why ? his answer is 1 sec billing. TATA DOCOMO simple USP is "PER SECOND BILLING". To an end customer it saves lot of money, since so long one minute billing from other operators are charging a same amount for 1 sec as well as 59secs of call duration. Those mobile operators billing is technically wrong. Phone usage should be billed based upon ERLANGS. A unit to measure Hrs of traffic used in an hr. It is a statistical measure of offered load. With this every second will have big difference on required link capacity and hence investment. Docomo's strategy of per second billing is in either way does good thing for indian mobile communication industry. Soon all the other operators may have to follow similar frame work. TATA GSM has become number one in terms of user addition Thanks to per second billing. BSNL has started billing as per sec pulse. Recently TRAI's chairman suggested similar norms.
We may ask all the operators to consider per-second pulse as a mandatory tariff option along with their other tariff plans, Even there (in per-second tariff plan), they must ensure to bring out clearly all the riders and caveats" Telecom Regulatory Authority of India (TRAI) Chairman J S Sarma told reporters on the sidelines of the International Telecommunication Union conference in Geneva.

TRAI has further clarified that "It will mandate Mobile operators to add per second billing plan as one of the plan". That means operators can have their existing plan as well. This will not affect 100% of TATA DOCOMO's USP. Operators will be allowed to further innovate new plans and ideas to attract more customers. TRAI is due to release another consultant paper on the same.
http://profit.ndtv.com/2009/10/08161634/Persecond-tariff-wont-be-man.html
Glad to hear the update from you. Thanks to TRAI for additional clarrification