The nine men from London and Birmingham rang their victims pretending to be police officers and claiming criminal activity was taking place on their bank accounts or at their bank branch.
After getting their trust they were persuaded to hand over large amounts of cash, often their life savings.
In total they conned six people out of £39,500 and tried to gain a further £84,150 from 11 further identifiable victims.
Three of the victims died without seeing the fraudsters brought to justice.
Eight defendants who admitted conspiracy to defraud were Amanul Islam, Mizan Ali, Abdul Ali, Tanvir Ahmed, Mohammed Miah, Ruhin Khan, Ali Nuruddin and Junaid Patwary.
A ninth, Abu Kaher, was found guilty after a trial at Hull Crown Court.
Helen Wheatley from the Crown Prosecution Service said: “It was a systematically planned and highly organised operation.
“By posing as police officers, they cynically exploited the victims’ trust and conned them into handing over thousands of pounds.
“Sadly the losses have not only been financial.
“All of the victims have suffered emotionally as a result of the fraud and unfortunately three have since died without knowing what the outcome of this case would be.
“The CPS has worked closely from an early stage with West Yorkshire Police and Humberside Police during a complex investigation which lasted two and a half years.
“We were able to provide ongoing advice as the investigation broadened from the initial arrest of two defendants for one fraud into the building of the current case, with nine defendants being sentenced today for their parts in a widespread conspiracy, eight of whom pleaded guilty in the face of the overwhelming evidence against them. I hope the sentences will be of some comfort to the victims and their families.”