The Anti-Terrorism Squad (ATS) has been put on the trail of certain mobile numbers suspected to be used by anti-social elements. Last month, the Mumbai police commissioner had launched a drive to check the credentials of all cellphone users, who had activated their services by submitting fake documents.

Following the drive, the Mumbai police discovered that there were in fact hundreds of subscribers who had submitted fake residence proof and other documents to the dealers. All the dubious numbers have now been forwarded to the ATS. “We have listed certain numbers which we believe may have been misused. Investigations are on to locate the users,” said ATS chief Rakesh Maria.

SIM cards are usually activated about 30 minutes after required documents — address proof, identity cards — are submitted by the dealers to service providers. After this, the service providers usually take a day to complete verification of the documents.

“In case of certain numbers, it was found that some of the users made several calls from the time their card got activated till it got disconnected after they failed verification,” a senior officer from the ATS said.

During the 26/11 attacks the 10 terrorists who entered India had used prepaid SIM cards obtained in West Bengal and Delhi. These cards were taken to Pakistan and given to the terrorists who misused them in India during 26/11.