The euphoria over the life-time validity offers of cellular operators may be short-lived as Trai has initiated an exercise to go deep into the matter to see its viability.Trai has undertaken a suo-motu exercise to see whether the concept of life-time validity being offered by the mobile operators on pre-paid cards with a one-time entry fee was viable."We will look into all aspects concerning the schemes, and may take some action if required," a top Trai official told PTI, adding the regulator would come out with its decision within a day or two. Tata Teleservices was the first player to offer two-year validity on its pre-paid card, and the move was strongly opposed by Cellular Operators Association of India (COAI) saying it was tantamount to predatory pricing.However, no operator could stand losing the race in adding new subscribers, and this had virtually triggered a tariff war among the service providers.To begin with, Bharti launched its life-time vaidity card with a one-time fee of Rs 999 followed by Hutch, Reliance, MTNL and BSNL.Idea cellular went a step ahead by offering similar services in both pre-paid and post-paid segments - thus raising doubts over the viability of these schemes.