Regulator Ofcom is threatening fines of up to £50,000 on companies behind the growing problem of silent calls, when you answer the phone and there appears to be no-one at the other end of the line.
These were once almost exclusively made by 'heavy breathers' who get a kick out of calling women anonymously.
But far more common today, and no less disturbing for some people, are silent calls made by automatic systems used for telesales, market research, debt collection and other financial services.
These ring numbers from a list until they get a reply, when the call is switched to a call-centre operator - if one is available.
If not, the line simply hangs. Scanning systems building lists of numbers do not even bother to get an operator: they simply register the phone as 'live'.
Complaints to BT about silent calls are currently running at about 80,000 a month and a phone owner receives an average 5.7 a month.
An Ofcom statement says the organisation will take 'swift and decisive' to ensure companies comply with a new set of requirements for call systems.
These require that more than three percent of live calls can be silent, and that if no operator is available within two seconds then a brief message must be played containing the name of the organisation responsible - which, as Ofcom points out cannily, is not necessarily the same as the one actually making the call.
The message should contain no marketing information and should provide a free or basic-rate number via which a phone owner can avoid further calls from that organisation.
Unanswered calls must be allowed to ring for 15 seconds before being cut off, and there must be no repeat call with three days.
The Calling Line Identification number must be made available to which return calls should be charged at no more than the national rate.
Ofcom says that if you phone company cannot help you prevent silent calls there is a complaint line at 0207 981 3040 or 0845 456 3000, which may be cheaper for some people.
Call-system specialist Netcall claims its Queuebuster product always always ensures an operator is available before making a call.
Product manager Richard Farrell said silent calls 'can cause worry and inconvenience and contribute to the negative perception of the contact centre industry.'
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