The UK telecoms regulator Ofcom is to investigate seven marketing firms over nuisance 'silent calls'.
Silent calls are an irritation for many householders
Ofcom said it would look into whether they had breached the Communications Act by misusing automated call systems.
Silent calls can occur when the automated phone systems used in marketing call centres generate too many calls for operators to deal with.
If no operator is available the line is terminated, meaning the person who answers the call hears silence.
Silent - or short duration - calls can also be caused by firms trying to send faxes to ordinary phone numbers.
Ofcom says that the total number of silent calls made by telemarketing firms in the UK is "unquantifiable", although it says BT gets about 160,000 complaints about such calls each month.
Ofcom said it had received complaints from members of the public about three of the firms - Promote IT, Toucan Telecom and The Listening Company Ltd.
The other four firms - ANT Marketing UK, Thompson Directories Ltd, Firestorm Marketing Ltd and Fax Information Services Ltd - were to be investigated following Ofcom's analysis of BT data on short duration and silent calls.
Under the 2003 Communications Act, Ofcom can fine a company up to £5,000 for each contravention of the regulations.
It can also issue an enforcement notice to make the company change its practices and "remedy the consequences of the misuse", which can include awarding compensation.
Code of practice
Four of the companies under investigation are members of the Direct Marketing Association (DMA).
The DMA welcomed Ofcom's action and said it would be liaising with the watchdog over the issue.
"The DMA has a very stringent code of practice which all its members have to comply with," a DMA spokesperson said.
"The DMA takes any breach of the code of practice very seriously."
Earlier this week, the DMA introduced new guidelines to its members, after its own research showed silent calls made 22% of people anxious. Under the new code of practice, DMA members must display a "caller line identity" so people will know who is phoning them. Consumers must be able to use this number to make a free call back to the company if they wish.
The DMA is also be setting up a database listing the free call-back numbers and the names of the companies using them.