High-flying executives and VIPs will now find it hard to keep their mobile numbers from flashing on others' screens. The Telecom Regulatory Authority of India has instructed telecom service providers not to offer services that restrict caller identification under normal circumstances.

An order issued by the telecom regulator on November 24 says, "Calling Line Identification shall never be tampered with as the same is also required for security purposes and any violation of this amounts to breach of security. Calling Line Identification restriction should not be normally provided to customers."

At present, a subscriber can bar the caller identification by paying a monthly fee of Rs 199. Approximately 5 per cent of the existing cellular subscriber base uses this facility.

Trai has, however, said if a subscriber provides a valid reason for not wanting his number flashed, the operator could restrict the line identification after verification. "It shall be the responsibility of the service provider to work out appropriate guidelines to be followed to prevent misuse of this facility," Trai has said.

It has added that such subscribers should be listed in a password-protected website with their complete address and details so that authorised government agencies can view or detect misuse of the facility. In case of international long-distance services, calls without identification will not be permitted.

The move comes after security agencies brought to the notice of the government the fact that the line identification restriction was being used by anti-national groups.