Authorities in the United Kingdom have arrested nine people in connection with a mobile phone and SIM crime syndicate, which used the cards to siphon off millions of dollars from Telefonica's UK mobile phone brand O2.
The City of London police said the group pulled off its heist by using purchased SIM cards to dial premium international phone lines, some of which cost $17 a minute. The group's outbound calls had reached fever pitch by the time it was axed, calling the premium numbers 24/7, the police said.
On Wednesday, officers seized around $26,000 worth of mobile phones, still in their boxes, which the group had purchased at London High Street stores and online.
The phones were then handed to the mastermind of the operation, who separated the SIM from the phones, sold the phones offshore and went on to use the SIM to call premium international numbers that had been established by the gang.
Police found hundreds of SIM cards, a pile of cash, laptops, computers and Nigerian 419 scam "advance fee" letters.
The scammers netted £1.2m in July alone, according to a report by The Guardian.
Detectives began working with O2 after the carrier noticed some customers racking up massive bills on the special numbers. The problem for the carrier was that it was required to pay the fees as they occurred, and only became aware of the scam after it tried to charge customers.
"Our investigation found a crime gathering momentum. Each month more SIM cards were being used to make more phone calls to premium rate lines at more expense to the network provider," said City of London detective superintendent Bob Wishart.