Silent calls can irritate or even scare consumers

The ten-fold rise in the maximum fine will come into effect this spring.

Silent calls happen when automatic dialling machines ring potential customers but generate more calls than the call centre staff can deal with.

The decision follows a consultation launched late last year by telecoms regulator Ofcom which showed support for raising the maximum penalty.

Trade & Industry Secretary Alan Johnson said silent calls were "annoying and distressing".

"I am increasing the maximum penalty to deter companies that make these nuisance calls," he said.

New rules

Ofcom is also introducing three new rules for the industry:

• Abandoned call rates must be below three per cent of all calls made in any 24 hour period for each campaign.

• All abandoned calls must carry a short recorded information message identifying the source of the call.

• Calling line identification (CLI) must be included on all outbound calls generated by automated calling systems. CLI allows people to dial 1471 and access the telephone number of the person or organisation calling them.

Ofcom decided to step up its action after it investigated seven companies which had been accused of making nuisance silent calls.

It ordered four of them to cut their rates of abandoned calls to less than 3%.

The regulator's action appears to be having some effect.

The number of nuisance calls being reported to BT each month has been halved from 160,000 to 80,000.