Reliance Infocomm and Tata Teleservices may be forced to change the mobile numbers of their subscribers, with the Telecom Regulatory Authority of India likely to recommend that all code division multiple access operators keep 9 as the first digit.

At present, mobile numbers of Reliance Infocomm and Tata Teleservices subscribers start with 3 and 5, respectively.

The change, initially proposed by Bharat Sanchar Nigam Ltd and the department of telecommunications, is being opposed by the CDMA operators, which have a subscriber base of over 5 million. The GSM-based cellular operators are also in favour of the change.

Trai officials said though a final decision on the issue was yet to be taken, the logic behind changing the number scheme for CDMA operators was to bring all mobile numbers on a uniform platform.

"Under the unified licence, there has to be some mechanism by which consumers can differentiate between a mobile and a fixed-line service. The numbering scheme is one such way. This is important because different services have different tariffs, and a consumer should know how much he will have to pay before making a call," an official said.

Sources in BSNL said the CDMA mobile numbers would have to change for interconnection. "Interconnection for mobile phones is different from fixed-line phones. If we are not able to differentiate between the calls, how are we supposed to offer interconnection," said a BSNL executive.

Basic operators, however, argued that the move would affect their subscriber base. They said if Trai were to change the numbers, they would have to take into account the growth in mobile subscription.

"One cannot change telephone numbers on a monthly basis. Trai has to device a method that will not necessitate a change in numbers even when we have 100 million subscribers. The move being considered now is only a short-term remedy that does not benefit anyone," said a basic operator.

Trai officials said as per the telecom department's report, level '9' could accommodate up to 450 million telephone numbers and, therefore, there was no question of running short of numbers in the wake of phenomenal growth in mobile subscribers.