A sophisticated phone fraud scheme which targeted large numbers of Vineyard residents last week, seeking access to their bank details, appears to have fooled very few people and netted little for the perpetrators, Island banks reported this week.

The phone calls, which began on Thursday night, purported to be from local banks, informing customers their bank cards had been suspended. The computer-generated voice on the line asked them to press one to be transferred to the security department, so the card could be re-activated.

Anyone who followed the prompt was then asked for account details. But very few people provided them.

“I don’t think they got an awful lot, which I guess is a credit to our customers here,” said Paul Watts, senior vice president at the Bank of Martha’s Vineyard.

As of Wednesday this week, only one customer of his bank had reported having given details to the scammers. That account holder had contacted the bank the following day, and transactions on the card were stopped. “They didn’t lose a dime,” Mr. Watts said.

Richard Leonard, the chief operating officer and executive vice president of the Martha’s Vineyard Savings Bank, said only a handful of his bank’s customers had responded to the requests for account information.

“There were a couple of [subsequent fraudulent] transactions for very small amounts,” he said.

Calls continued to come in on Friday night and again on Sunday afternoon, but in smaller numbers. News of the fraud attempts spread quickly, by word of mouth, through local media and warnings posted quickly on the banks’ Web sites.

The phone scam, of a type which has become widespread across the country over the past couple of years, works by systematically calling numbers within a particular area code, taking the odds that the person who answers will have an account with a given local bank or other financial institution.

The fact that someone gets a call does not reflect any breach of bank security; it is entirely random. As an example, Mr. Watts himself received a call on Thursday night, referring to an account he allegedly had with his competitor bank, the Martha’s Vineyard Savings Bank.

“My wife was quick to recognize, just amazingly, that we didn’t have an account with them,” Mr. Watts said.

It was a common experience. The banks reported a large number of the people who contacted them were bemused by the fact that they had been told an account had been suspended when no such account existed

Anecdotal evidence — no one can be sure exactly how many calls were made — suggests most calls named the Martha’s Vineyard Savings Bank, although this could be skewed by the fact that it has the largest number of account holders.

A few customers of the third local bank, Edgartown National, also were contacted but none was taken in by them, because the calls did not identify the bank by name.

“They all seemed to refer to Martha’s Vineyard Savings Bank,” said Greg Berks, vice president and chief operating officer of the bank.

Not only do the calls go to random numbers, but they appear to come from random numbers. Customers’ caller ID showed the calls as having been placed from various parts of the country, including California, Chicago, Florida and elsewhere.

“I don’t know exactly how the [scammers’] technology works, but I’m told they use VOI [Voice Over Internet] protocols to mask the real originating number,” Mr. Leonard said.

This means neither the individuals contacted, nor the banks, nor bank regulators nor phone companies can trace the origins of the calls. The scam counts on catching people when they are vulnerable.

“They did this late at night. I guess they figured people would be tired and would spit the information out before they fully realized what they were doing,” said Mr. Watts.

“They’re well organized. They hit, hit hard, and then moved on. I guess if they only get 25 accounts, it’s probably a good night’s work.”

All the bankers said people should remember that no bank would contact a customer and request information it already had.

“We harp on this all the time with our customers, that there is no legitimate bank anywhere that will call you and ask for your social security number, your mailing address, checking account number, your pin number,” Mr. Watts said.

Mr. Watts also was seeking this week to put customer concerns to rest on a second issue — the takeover of his bank’s parent company, Sovereign Bank, by the giant Spanish-based multinational, Banco Santanda SA.

Sovereign was left vulnerable after recording big losses over the past 18 months related to the mortgage crisis. Over the past couple of weeks its share price had fallen sharply, from more than $8 at the end of last month, to less then $4 when Banco Santanda moved on Monday this week.

The Spanish bank already held almost a quarter of Sovereign’s stock. The deal for the rest of the bank was worth $1.9 billion, and valued Sovereign shares at about $3.81, a premium of about 3.5 per cent on their market value immediately before the deal.

Mr. Watts said the takeover would make no difference to the bank’s Island operations.

“At this point they plan no name change, no contraction of employees. They do the same kind of loans we do. They are largely a retail and commercial lender,” he said.