Mangaluru: A 43-year-old man from Mangaluru, Karnataka, has allegedly lost nearly Rs 24 lakh in a sophisticated cyber fraud after being tricked into approving a fake 4G-to-5G SIM upgrade request. Investigators said the fraudster, posing as a customer care executive of a mobile service provider, gained control of the victim’s mobile number and subsequently accessed his banking and credit card facilities to transfer funds to multiple accounts.
A case has been registered at the CEN Crime Police Station, and an investigation is underway.
According to the complaint, the victim received a phone call on July 8 from a person claiming to represent his mobile service provider. The caller informed him that his existing 4G SIM card had to be upgraded to a 5G SIM and, during the conversation, shared some of the victim’s personal details to establish credibility.
After the victim agreed to the upgrade, the caller instructed him to approve a request that would be sent to his Gmail account. He was also told that his mobile network would remain inactive for a few hours as part of the upgrade process and that there was no reason for concern. Trusting the caller, the victim accepted all the prompts received in the email.
Shortly afterwards, his SIM card stopped functioning completely. When the network was not restored after several hours, the victim contacted the caller using another phone. The fraudster repeatedly blamed the disruption on technical server issues and assured him that the service would be restored soon. By the evening of July 9, when the SIM was still inactive, the victim began to suspect foul play.
He then visited a local customer service centre of his mobile operator, where officials informed him that the company does not upgrade SIM cards through unsolicited phone calls or ask customers to approve requests sent through email. Realising that he had been deceived, the victim immediately removed the inactive SIM card from his phone and contacted his bank.
During verification, he discovered that Rs 3 lakh had already been transferred from his bank accounts. Police said the fraudster had also obtained an instant loan of Rs 9 lakh using one of the victim’s credit cards. The loan amount was first credited to the victim’s bank account and then swiftly transferred to other accounts.
Investigators further found that the accused had used three different credit cards to transfer an additional Rs 4.10 lakh, Rs 3 lakh and Rs 5 lakh. In total, unauthorised transactions amounting to Rs 23,98,138 were carried out from the victim’s bank accounts and credit cards between July 8 and July 9. Since the fraudster had gained control of the victim’s mobile number, OTPs and banking alerts were allegedly intercepted, preventing the victim from detecting the transactions in time.
Cybersecurity experts said such frauds often involve SIM swap or mobile number takeover techniques, allowing criminals to receive one-time passwords and authentication alerts linked to banking, credit card and digital payment services.
According to the Future Crime Research Foundation, mobile numbers have become the primary authentication channel for most digital financial services. Users whose SIM cards suddenly stop working or lose network connectivity without explanation should immediately contact both their mobile service provider and their bank instead of assuming it is a routine technical issue. The foundation also advised users to verify any request relating to SIM upgrades, KYC updates or network migration directly through official customer care channels before approving emails, links or prompts.
