A Salt Lake resident got a call from a man who claimed to be from the “technical support team” of his office and sought remote access to his computer to delete an antivirus file installed earlier.

A Ballygunge resident received six calls from as many unknown numbers within an hour and a half. All the callers said they had received a missed call from his number.

In both cases, the recipients smelt a rat and disconnected the calls before the callers could obtain any information. However, many are clueless about how to react to such fraudulent calls and end up losing money.

Senior police officers said people getting cheated through remote access to one’s phone or computer system is not uncommon. However, engaging someone who says he is only responding to a “missed call” or is from the tech support team in the office of the person called could mark a new trend, the officers said.

People working in the field of cyber security suspect that such calls are being generated using a software.

“These are fake calls that are generated through a software that uses the VoIP interface to place a call,” said Sandeep Sengupta, director of the Indian School of Anti-Hacking (ISOEH).

“The person doing this has to put a phone number in the software and initiate a call to the target’s mobile phone. The target will get a call from the number that has been inserted through the software. The actual owner of that number will have no clue about it.”

The police are advising the recipients of such calls to report the cases to the local police station or the cybercrime cell.

A senior police officer at Lalbazar said there have been many instances of Calcuttans getting phone calls and are being asked to share their computer screens on one pretext or another.

In the case of the Salt Lake resident, the caller pretended to be a colleague but his lies were caught when he asked for the official email ID of the person.

Metro spoke to several police officers and cybercrime experts seeking their opinion on how to react if one receives such a call:

• If an unknown person calls saying he or she has received a call from your number but you have not called that person, stay calm and end the conversation at the earliest
• Do not divulge details such as your name, location and profession
• If the caller lingers and falsely accuses you of calling his or her number, tell him or her that you have not made any such calls
• If the caller continues to nag, terminate the call and report the matter to the local police
• If the caller further drags the matter, approach the Telecom Regulatory Authority of India (TRAI) for your call details. The records will show that there were no outgoing calls from your number to the other number
• If an unknown caller (pretending to be a telecom operator or a colleague) asks you to download a software, hang up at once
• If an unknown caller asks you to click a link, don’t do that
• Never answer a video call from an unknown number
• Police should be informed about repeated harassment by unknown callers.