US crackdown on illegal computer-operated robocalls
The US government has announced a "crackdown" on computer-controlled, pre-recorded phone calls.
The Federal Trade Commission is calling on telecom and marketing industry leaders to attend a "summit" about the issue in Washington on 18 October.
It said it wanted to explore innovations that could let it trace where such calls come from and prevent the use of faked caller IDs.
The US made it illegal to make unwanted automated calls in 2009.
The law says marketers must have written permission from a user before such calls can be made. Exceptions are made for surveys or if the subject matter is political or to do with a charity.
"The FTC hears from American consumers every day about illegal 'robocalls' and how intrusive they are," said the agency's chairman Jon Leibowitz.
"We're ratcheting up our efforts to stop this invasion of consumers' privacy."
The agency said it had already imposed penalties totalling $41m (£26.3m) since the change in the law.
These include the seizure of $3m worth of assets from SBN Peripherals, a Los Angeles business trading under the name Asia Pacific Telecom.
The firm was accused of making about 2.6 billion pre-recorded calls claiming it had urgent information about consumers' credit-card and vehicle insurance.
The FTC said users who had pressed "1" to hear more information had been transferred to human operators who had tried to sell them inferior or worthless products.
The agency was also responsible for shutting down another company, which it alleged had used at least 10 different names to defraud 13,000 people out of a total of about $13m. It said the business had made bogus promises that it could secure them refunds.
However, experts believe many offenders operate by routing calls via the internet from offshore centres, making it hard for the US to completely eradicate the problem.
The FTC has said that members of the public are invited to attend its meeting in October, adding that it would answer questions about the issue via Twitter and Facebook on 17 July .
The UK also requires user-consent for automated phone messages if the recipient does not have the opportunity to speak to a real person during the call.
In addition users are able to opt out of all unsolicited marketing messages by contacting the Telephone Preference Service .
Despite this, the UK's Information Commissioner's Office recently reported a 43% jump in the level of complaints it had received about unsolicited electronic marketing messages last year, with automated phone calls the most commonly complained about.