In separate directions to Bharti Airtel, Vodafone, Idea Cellular, Reliance Communications, Tata Teleservices (TTSL), Reliance Telecom and Aircel, Trai asked them to disconnect all mobile numbers ported from the network of Loop Telecom.
The regulator also asked the operators to submit a compliance report to it in 15 days.
The directive follows a complaint by Loop Telecom, which had said that 5,923 numbers have been ported out illegally from its network to various operators.
The 21 licences of Loop Telecom had been quashed by the Supreme Court in February. Following the SC order, the operator had said it would shut down its business in India.
However, Loop Telecom complained that operators ported out those numbers which were not being used by its customers.
In its complaint, Loop Telecom said that it never activated these 5,923 numbers in the system for subscriber use and this port out seems to be the result of some "fraudulent activity."
Airtel, which also ported out from Loop Telecom, however, said it continues to comply with all regulatory guidelines.
"All MNP requests are processed as per process as laid down by DoT / TRAI and all port-in requests are cleared by MNPSP ( mobile No portability Service provider). All port ins directed by the authority to be disconnected have been disconnected and compliance report has been submitted at the local TERM Cell," a Bharti Airtel spokesperson said.