The prescribed ceiling for mobile number portability rates was Rs 19, so far.
Trai's latest move means that subscribers cannot be charged more than Rs 4 for their network port out requests but the recipient operators are "free to charge" a lesser amount from them for Mobile Number Portability (MNP).
Notifying the regulation to this effect, the Telecom Regulatory Authority of India (Trai) said it has "decided that the per port transaction charge may be reduced as the costs of operations of Mobile Number Portability Service Providers (MNPSPs) have substantially gone down and the volume of MNP traffic has increased".
Trai had initiated a consultation process to review these charges in mid-December and followed it up with an open house discussion on the issue on January 16.
The authority has been of the view that considering the upsurge in the volume of porting requests with effect from July 3, 2015, and the financial results of both the mobile number portability service providers (MNPSPs), the ceiling of Rs 19 is "quite high" as compared to cost and volumes of transaction involved.