His initiative was spurred by the tragedy of a young girl who killed herself because she mistook her menstruation for a sexually transmitted disease. At the time, Britain was still recovering from the trauma of war and suicides were on the rise. Varah sought to calm the tormented through listening without judgment, an approach that has proved effective in the decades since.

In 1960, school principal Andrew Tu Hsueh-kwei set up the first Samaritans unit in Hong Kong to help a growing number of people struggling to adapt to rapid social changes, especially students depressed by poor results in public exams. Suicide prevention was an unfamiliar notion, as was the concept of mental illness. 'At the time, health services were focused on the physical side. Nobody was talking about mental health,' says clinical psychologist Paul Wong Wai-ching of the University of Hong Kong's Centre for Suicide Research and Prevention.

The Samaritans began with a Cantonese and an English-speaking division, but the latter reformed in 1973 as a separate multilingual charity called the Samaritans while the Cantonese unit was named the Samaritan Befrienders. A third group was set up 12 years ago with government and other social groups under Befrienders International (which connects the Samaritans globally) to meet the growing needs of Cantonese speakers - the Suicide Prevention Services (SPS).

Although the Befrienders and the SPS provide more comprehensive help that extends beyond a 24-hour hotline, all three groups uphold Varah's belief in empathetic non-interference. Volunteers pledge unconditional emotional support with anonymity and confidentiality. 'It's the only way we can win the trust of callers and make them feel they can share their darkest fears with us,' says Chamberlain. 'But no bond is allowed. We discourage dependency because we want to empower callers and get them to decide for themselves.'

The suicide prevention groups find that people can be pushed over the edge by problems ranging from guilt and addiction to infidelity and debt. Hotline volunteers help by providing an immediate emotional outlet for depressed callers, offering an empathetic and non-judgmental ear.

'It's most important to calm them down and let them know there's hope,' says psychiatrist and columnist Bruce Chan Kwok-tung. 'When they call it means they take the initiative to get help and share their pain and feelings.'

Ada Chan, who has volunteered at the Befrienders for 10 years, recalls the satisfaction of talking a woman out of an emotional maze. 'Her husband left her for another woman and she locked herself in a room for a week,' says Chan. 'She couldn't see anything beyond this one blemish in her life. I talked about her relationship with her husband and put together the whole picture like a puzzle. Then it dawned on her that she was mired in an emotional cul-de-sac.'

Befrienders chairman Robert Wong Yao-wing says anyone can be caught up by what appear to be insurmountable difficulties. 'They think the world will fall apart if a problem is not solved,' he says. 'Our job is to help them reflect on their feelings and let them know that we don't exist for one purpose.'

Hotline volunteers must not give advice. When it comes to soothing the suicidal, offering personal opinion is 'tricky and very dangerous', says Chamberlain. 'Advice is good when it's for something practical, like when you have a broken computer, but never on an emotional level.' Chan says: 'There's no way to get the whole picture from a 30-minute phone conversation. We only give strategic advice after building rapport with the patient face-to-face; non-verbal communication counts too.'

It takes a lot more than passion to man a suicide hotline; candidates undergo a year's training in communication techniques and must pass assessments before getting to help. '[Callers] are entitled to the best services available because it's a matter of life and death and we take it very seriously,' says Vincent Li Yiu-fai, a trainer with the Befrienders.

Volunteers should be open-minded, patient, caring, articulate - and have staying power under stress. 'When one volunteer told me he was freaking out on the way to the centre because he was afraid to take the calls, I told him to quit. I'm not being mean, but it's in the best interest of the callers,' says Li.

It's easy to be overwhelmed by the callers' misery, but volunteers have learned when to unload the baggage. 'We leave our personal lives at the door and take nothing away when we leave,' says Alice Yip, who volunteers at SPS.

The volunteers say they gain from their work. Chan, a bank officer, finds her hotline experience comes in useful when dealing with clients. 'I used to be intimidated by clients. But after I learned to handle unstable callers as a Samaritan, it became easy,' she says.

Yip says the friendships she gained are an unexpected bonus. 'We never work in isolation and we support each other,' she says.

'I understand more about myself and life as I put myself in [the callers'] place.'

The Befrienders and SPS recognise there are limits to how a hotline can prevent suicide, and refer those in need to social workers for further counselling. They also reach out to the community through educational programmes and services for people who suspect family members are suicidal. SPS places an emphasis on the elderly and organises visits to their homes. 'It's important to recognise these symptoms before it's too late,' says Robert Wong.

Aside from a dip last year, all Samaritan organisations have recorded a steady rise in calls over the years, echoing the increase in suicides which peaked at 1,264 in 2003. The Samaritans' 100 volunteers now handle some 30,000 calls annually. 'It's perhaps the most we can accommodate,' says Chamberlain, who hopes to recruit more volunteers to meet the need in an increasingly impersonal society.

'It's getting hard to get support from your social network,' says Bruce Chan. 'It's easy to blame society for the suicides, but it also has a lot to do with whether you can have someone to listen to you and care for you.'