New rules to prevent consumers being harassed by silent calls will be introduced from tomorrow.
Firms that breach these regulations face a fine of up to £2 million from telecommunications regulator Ofcom (see the Beat Cold Callers guide).
Thousands of householders complain every year that they are targeted by firms with repeated nuisance, and sometimes distressing, calls where they hear nothing when they pick up the phone.
What are the regulations?
Companies making a sales or customer service call must not telephone that person again on the same day if they've already tried but there was silence at the firm's end.
This may sound strange but many calls made by outbound call centres are often automated so agents do not manually dial themselves.
Before a call is routed to an agent, software used by the company determines whether a person or an answer phone has picked up. Only where it's a human being will the call be transferred.
But glitches mean the software sometimes wrongly identifies a person as an answer phone in some cases, such as when there is background noise
When this happens, the call is not re-routed and the recipient hears silence.
The rules apply to any call made by a UK company whether in the UK or from an offshore call centre.
The exception to the new regulations is that firms can phone again if they know one of their agents will definitely be on hand to take the call.
Archna Luthra, MoneySavingExpert.com consumer products analyst, says: "This is a step in the right direction but it is not fool-proof.
"If the regulations are to be enforced, it relies on consumers reporting calls to Ofcom. This won't stop companies from calling outside the UK, which is still a massive problem."
Previous Ofcom intervention
Abbey (now Santander), Barclaycard and Carphone Warehouse are among the big name firms to have been fined over silent calls in the past.
In 2006, Ofcom introduced rules to address a separate problem, which it says it largely fixed.
This was when a call centre was too busy or there were not enough agents to take the call after the automated dialling, so the customer would hear silence when he or she picked up.
Following that intervention, firms must leave an automated message and not call again when an agent is unavailable.
Ofcom received over 9,000 complaints in 2010 about silent calls. Over 70% of consumers who complain say that they have received two or more calls in a day from the same company, often over a period of days or weeks.
Ofcom chief executive Ed Richards says: "Silent and abandoned calls can cause significant consumer harm.
"Ofcom has given sufficient warnings to companies about silent calls and is ready to take appropriate action against those companies who continue to break the rules."
How to tackle silent calls
If you're a victim of silent calls you can report the firm to Ofcom.
To find out who called you try dialling 1471 to get the number and look it up on the internet or call it back.
If the caller withheld their number, you can call your telephone provider's nuisance number helpline, stating the time and date of call to attempt to trace the number.
Also, if you register with the Silent Callguard Service you should get fewer silent calls as your number will go on a list given to marketing firms telling them which households NOT to call.
Further reading/Key links