As far as I could interpret, this is not a TRAI rule. Like I mentioned in my earlier posts, TRAI only says that the number cannot be "deactivated" if you have sufficient balance in your account (at least Rs 20). The industry stalwarts have found a loophole - they keep the number "active", but with no outgoing or incoming facility - if the minimum Rs 23/24 recharge is not done. Thus, they are abiding by TRAI rules since they haven't deactivated your number, and they get to suspend services too.Not sure who invented it but it's a rule from stone age, i mean in 2002-3 we used to recharge 330 to get 300 talktime evey month in BSNL and that talktime expire if we don't use it. They are now bringing it back.
IMO, TRAI needs to revisit the meaning of "active" number and specifically mention that an active number means outgoing and incoming calls, SMS, MMS, and Internet is active.