Householders have been told to cut off con artists after a scam where they tried to get bank details out of people after a series of silent calls made to Hartlepool.
The Trading Standards team at Hartlepool Borough Council says it has received a number of reports from the town where up to 10 silent calls have been made to landlines.
On occasion, they have been followed up with a call from someone claiming to work for a company which sells devices which blocks nuisance calls.
The calls come from a Glossop number, which starts with the area code 01457, and is believed to belong to a scam group.
Anyone who gets such calls have been urged to put the phone down.
Neil Harrison, senior trading standards officer at the council, said: "We've had three or four calls telling us people have received anything from four to 10 silent phone calls starting from around 8am this morning with 20 minutes and up to an hour or so between calls.
"In some cases there has been a follow-up call asking if they would like to by a call blocking device and for credit card details.
"We are asking people not to give out any of their financial information and we know the number from one of the call takers, who used 1471 to get the details, and by looking up the number it's come up as a well-known scam.
"From the number of calls we've had, it seems in Hartlepool has had a spate of them and we know that sometimes they target a specific area code.
"We would say straight away, don't give anyone your information, hang up.
"Unfortunately, it won't stop them, but as long as they know they're not going to get any money and they're not going to get any information, they'll move on.
"We have also heard they have claimed to be from the Telephone Preference Service, which is against these kind of scams in the first place and the TPS would never call someone."