Talk about thankless tasks.

Have you ever spared a thought for the person on the other end of that telephone helpline, that most modern of employees - the call centre worker?

So controversial have call centres become that they have earned the nickname "the coal mines of the 21st century".

It is estimated that 350,000 people - more than 1% of the UK working population - spend their days fielding calls on topics as diverse as car insurance and health problems.

The lot of these workers has received increasing attention in recent months, amid fears of poor working conditions in a rapidly growing sector, which employs more people than coalmining, steelmaking and vehicle production combined.

Allegations range from the bullying of employees to meet impossible targets to suggestions that call handlers are treated as little more than machines.

Workers at NHS Direct, the health service helpline, were apparently told to pretend to be answer machines when the system was hit by technical problems over Christmas.

Call centres make good economic sense to companies. By shifting customer service from the High Street to a small number of sites, they stand to make considerable savings.

Such economies can be increased by locating in a depressed area with a surplus of cheap labour and government subsidies.

However, with a staff turnover of some 30%, it looks as though the call handlers are not enjoying the fruits of this telecommunications boom.

Jonathan, who works at a major call centre in northern England, has seen this staggering turnover at first hand.

"Two-thirds of the people who join us don't make it past their second month. Most [of the others] leave within a year," he says.

Companies have been accused of taking a cavalier attitude to happiness of their staff, preferring to hire agency workers rather than investing time and money in a full-time workforce.

Although this practice is becoming less widespread, partly thanks to union action, Jonathan says attitudes to staff have changed little.

"They'd like to hire and fire at will. They can't predict call volume and so can't be sure how many staff they'll need.

"When the company has a problem with its products, calls from customers start to flood in and there's no one to answer them."

The technology which has allowed the growth of call centres has also enabled companies to keep a close eye on productivity.

"Managers get a print-out of call handling times, an employee's 'wrap' - the time spent dealing with a customer's problem after they ring off - and the time spent away from the phone on short breaks.

Nature calls

"These trips to the toilet or the water cooler must not exceed 10% of the working day."

Targets are set for every aspect of the job. While employers claim this is to ensure high standards of customer care, such close monitoring can increase the stress levels of workers.

Having to deal with frustrated and abusive callers can compound the misery of working at a call centre.

"When new people say: 'We shouldn't have to put up with abuse' you know they're not going to last long," says Jonathan.

"I'm experienced and often see trouble coming, but some colleagues complain 50% of their callers turn nasty."

"Nasty" seems a rather mild term for the catalogue of obscenities and death threats Jonathan describes.

Obscene calls

"It's water off a duck's back to me - I'm only doing it to get paid. If I was expecting a career in customer service, I'd be upset."

Career satisfaction is only one side of the picture. The Health and Safety Executive (HSE) are examining the special hazards of working in call centres.

Initial findings suggest the huge, open plan offices associated with call centres can quickly become unhealthy working environments.

With high noise levels and uneven air conditioning battling the heating effect of numerous computer terminals, workers' hearing, sight and lungs are all at risk.

The HSE has also suggested limiting time spent taking calls and using computers to just 60% of the working day, in a bid to prevent repetitive strain injuries.

Such problems are arguably the malady of many modern offices, but next time you're held in one of those infamous call centre queuing systems - spare a thought for the voice on the other end of the line.