Fraudsters are targeting UK consumers with eight scam calls every second, according to research by the Money Advice Service (MAS).
A survey of 2,014 UK adults revealed that more than six in 10 (63%) received a suspicious call over the past 12 months, with 43% targeted in September alone. MAS said this equated to eight calls taking place every second.
MAS said scammers used modern technology to target people and claimed to represent a range of familiar companies and organisations such as the police, banks or utility firms.
Nearly one in five (19%) received a call where someone was impersonating a genuine organisation, and 6% said the call came from the number belonging to the organisation scammers were trying to impersonate.
MAS explained conmen used software to mimic the caller ID number of the organisation they were impersonating, known as "telephone spoofing".
Another technique is the "no hang-up scam", according to MAS. More than one in 20 (6%) said someone had tried to gain their trust by asking them to call the number on the back of their debit or credit card.
MAS said fraudsters would keep the line open, "spoof a dial tone" and an accomplice would impersonate whomever the victim thought they were calling.
MAS said the elderly and those living alone were most vulnerable, with those over 55 most likely to fall for a scam. It said they were more trusting of officials claiming to call from their bank and were less aware of the technology available and tactics used by con artists.
Nick Hill, money expert at MAS, said: "While telephone fraud is not a new phenomenon, modern technologies make it easier for scammers to target and exploit victims.
"These criminals are clever and creative, using the latest technology to impersonate genuine organisations. They can hijack a bank's telephone number as well as use scripts and systems that banks are likely to use - meaning it's harder than ever to identify a scam call."
Separate research by Portus Consulting has found nearly half of people aged 55 and over have been approached by suspected scammers more than once since pension freedoms were introduced in April.
Based on a survey of 789 people, the firm said 24% were offered products to invest their pension savings in without being told what they were while 69% were offered a free pensions review. More than a quarter (27%) said the suspected scam involved an "exotic" investment scheme promising "attractive levels of return".