Tom Francis is not my real name. My real name is the one on the front of my books. But I’ve been working as a Samaritans volunteer for the last two years. And when I’m on the phone the rest of my life is put to one side and the only thing that matters is the person on the other end of the line.

It’s often challenging. Sometimes it’s desperately sad. Sometimes it’s uplifting. Every now and then it’s very funny. It’s one of the most satisfying things I do, it’s made me a better listener and I’m now a lot more grateful for all the good things in my own life. It’s put me in contact with the most extraordinary range of people and every so often I go home after a shift knowing that someone has been helped at a crucial moment in their life by hearing me say, “Do you want to tell me a bit more about that?”

I’ve heard some extraordinary stories, none of which I can share because the Samaritans is one of the very few helplines that can offer callers complete anonymity and complete confidentiality. But I can tell you some of the reasons why they get in touch.

We listen to people who are feeling suicidal. We listen to people buried under crippling debt, to people going through bitter divorces or bruising child custody battles. We listen to people with long-term mental health problems, to people who are fighting the urge to harm themselves, to people haunted by voices and to people who believe that malign forces are controlling their lives. We listen to people who have been sexually abused and to people who are still being abused. We listen to people in prison. We listen to people who have been bereaved and people who have terminal illnesses. We listen to people whose relationships with their families, their co-workers or their employers have gone terribly wrong. We listen to people struggling with drugs or alcohol. Perhaps more than anything we listen to people who are profoundly lonely. Many of our callers fall into two, three or four of these categories.

Some of them are difficult, angry people. Some are charming and self-deprecating. Some are admirable. Many are apologetic for taking up our time. Some are distraught after experiencing events that other people might think trivial. Some are sanguine in the face of experiences that would destroy most of us.

What we offer them is something very simple: the opportunity to talk about what is troubling them for as long as they need. And we listen. We don’t try to cheer them up or change their minds. We don’t talk about ourselves, we don’t make judgments or give advice.

Only since working for the Samaritans have I come to understand how rare this is. In our daily lives we are always asking people, “How are you?”, but it’s rarely more than a friendly greeting. If someone were to reply, “I’m having a terrible time,” most of our hearts would sink, which is why people rarely say, “I’m having a terrible time.” When friends, colleagues or family members are in trouble it’s all too easy to tell them to be positive, to reassure them that things will get better or to tell them our own stories of being in a similar situation. We shy away from other people’s suffering. As a result the world is full of people trapped in dark places who never ask for help.

Only since working for the Samaritans have I come to understand how much being listened to and feeling genuinely heard can ease that burden.

We’ve all had callers saying they are sick and tired of being told to keep their chin up and to look on the bright side, and we’ve all had callers who thank us for just letting them talk. On several occasions I’ve waited for 30 silent minutes or more for someone to pluck up the courage to tell me things they’ve never been able to tell to another human being. It’s not always easy. If someone is planning to take their life, we don’t try to dissuade them. We encourage them to tell us about what they’re going through, however terrifying, however bleak. Research suggests that this reduces the number of callers who go on to take their lives, something you will know in your bones after you’ve taken a few of these calls.

Very occasionally we take calls from people who are in the process of ending their lives. We will always ask if they want an ambulance and we’ll call one out if they give us their address and can’t do it themselves. But if they insist that they don’t want medical help then we’ll stay with them for as long as they might be aware of a voice at the other end of the line. These are, for many Samaritans, the hardest calls and we’ve all had them. The compensation is the knowledge that someone hasn’t died alone.

We also take calls from prisoners and ex-prisoners, some of whom have committed violent or sexual crimes. We steer round the subject of their offences where possible and ask instead about what’s troubling them now. Sometimes these calls are difficult because of our instinctive distaste for someone who might have hurt or killed other people. Often the shock is discovering how ordinary they seem, how little difference there is between them and us.

And a surprising number of people abuse the service. Some want an argument. Some need to swear loudly at a stranger. Commonest of all are those who ring up to share their sexual fantasies: the majority are men who want to talk to female volunteers; and the majority can be identified in about 10 seconds, though it is occasionally difficult to spot the difference between the sound of someone having a panic attack and the sound of someone masturbating. In most cases we’ll tell the caller they can ring back at any time if they genuinely need to talk, then politely end the conversation.

I still turn up for every shift feeling a little nervous, and I hope I always do. None of us has any idea what to expect

I signed up partly because I missed the voluntary work I’d done after leaving college. I wanted to learn something new and I wanted to do something that wasn’t about me. So I went along to one of the information evenings at the local branch. The work sounded scary but intriguing, and they seemed like a warm, welcoming and very organised group of people. I passed the interview, took part in the reassuringly thorough training then did my first five shifts with a mentor sitting beside me.

I now do a shift most weeks, always alongside another volunteer. There’s a regular flow of tea and biscuits and it’s a rare day when someone hasn’t bought in a homemade cake for sharing. Some calls last five minutes, some last for hours. We’ve all had people call up just to sing to us then put the phone down, and we’ve all had people ringing to thank the Samaritans for getting them through a really difficult stage in their lives.

We answer emails and texts, neither of them the ideal medium for discussing difficult subjects, but they help us reach people who wouldn’t get in touch in any other way. Callers can also knock on the door and talk to us in person from 8am to 10pm.

I still turn up for every shift feeling a little nervous, and I hope I always do. None of us has any idea what to expect when that phone rings for the first time. By the second call, however, I’m starting to feel at home. And at the end of every shift I feel – paradoxically – happier, for reasons I still only half understand. Some of it, I suspect, is that I’ve had a few hours in which I’ve not had a chance to think about myself.

On top of this I’ve found myself a whole new community. There’s a book club, a summer picnic, a Christmas dinner. The group I trained with still go out for meals together. Volunteers are ordinary people and inevitably we experience some of the same problems our callers experience – bereavement, mental illness, family breakdown, unemployment … When it happens, we’re looked after. We do fewer duties or take a break from duties altogether. Someone from the branch stays in touch to check we’re OK, and if we need to talk then we have more than a hundred people to choose from.

But we have a problem. The number of callers has been rising steadily. Some of them, especially those who call in the small hours of the morning, now get an engaged tone, and that’s a worry. For many people it’s hard enough plucking up the courage to ring us in the first place. If we’re busy it might be the last time they try.

One reason for this surge is that it now costs nothing to call the Samaritans from anywhere in the UK or Ireland, and that’s a good thing. But there are less cheering reasons. Homelessness is rising, people are earning less money for jobs that are less secure. We’re also getting an increasing number of calls from people with long-term mental health problems who feel let down by the health service. Many of them have been told explicitly by doctors, nurses or social workers to ring us when they are in crisis. And we will do this happily. We will always answer as many calls as we can from anyone who needs to talk. But one volunteer can only pick up one phone at a time.

So ... if you want a challenge that could change people’s lives – including your own – go to our website, find your local branch and come along to an information evening.

• Contact the Samaritans for free from any telephone on 116 123. You can call even if you don’t have credit on your mobile, and the number won’t show up on phone bills. Or you can email jo@samaritans.org or go to www.samaritans.org to find details of your nearest branch, where you can talk to one of our trained volunteers face to face.

In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international suicide helplines can be found at www.befrienders.org

• Tom Francis is a volunteer for the Samaritans