A couple of weeks ago, my daughter Grace lost her iPhone. Grace is a 15-year-old with a diagnosis of autism and a severe speech delay. Some people would call her "non-verbal" but she can say a few words and if people don't understand she shows them a picture.

When Gracie was small, she used to have to carry a big book around to hold these pictures, but then the iPhone was invented and a very kind person gave us one to try. I was able to transfer all her pictures onto a folder on that phone and whenever we didn't have a picture, we could take a photograph and add that to her collection. Grace is considered to have an intellectual disability but she had no trouble navigating that iPhone, and she carried it around with her everywhere in an especially strong cover to protect against accidents.

With the help of a young Irish gaming developer called Steve Troughton-Smith, I was able to create an App to store and sort those pictures and in honour of my daughter, he called it Grace App.

These days Gracie, like many kids, has an iPad in school, and we have one at home for games and videos. Her iPhone, in its strong pink case with the shoulder strap, is kept purely for communication when she is out and about. No games, no YouTube, no internet - just the App that she helped to create and still uses every day.

So two Fridays ago, she comes home from school, goes upstairs to change, put her phone away (I thought) and then came downstairs to enjoy the long St Patricks day weekend. We don't really use the phone at home as she has the iPad so I didn't notice it was missing until the night before school when I start sorting out lunches and charging up iPhones. I looked everywhere in the house, tipped up washing baskets, dug through school bags and generally pulled the place apart with a rising feeling of anxiety. It was long flat so I couldn't ring it and I couldn't recall the last place I'd seen her with it.

There was a meeting at the school so I messaged her teacher to ask her to check, but there was no sign of it anywhere in the classroom. She must have lost it somewhere over the weekend, but where?

So I took to social media, posting a photo of the phone in its lovely pink cover, the area it might have gone missing and a request to share. I simply couldn't believe that someone had stolen it, but maybe someone, somewhere had picked it up and didn't know whose it was.

The response was enormous, 15,000 shares on Facebook and countless retweets on Twitter. Everyone wanted Gracie to have her "voice" back. Not all tweets were kind, one guy actually laughed when he saw we were looking for such an "old" model. But when I challenged him, he apologised profusely when he realised that "old" iPhones were very valuable to people like Grace.

And then several lovely people got in touch to offer me their old iPhone. One guy when he discovered that Gracie was "The" Grace" of the Grace App and I was its co-creator, asked me if I knew of any other autistic kids who could benefit as he actually had four phones to pass on.

I sure do, I said. You see, as a sideline to being a mum to two teenagers with autism and an app co-creator I also collect old iPhones for iPhones4autism.ie.

How does iPhones 4 Autism work?

It's not a charity as we don't really want cash, but a way to ensure that your old iPhone goes to a person with autism who really needs it.

With every new iPhone release, we keep an eye out for anyone talking about upgrading and encourage them to consider donating the old one, to us. We've had about 20 old iPhones and 2=two iPads donated in the last four years. I restore them to factory settings, put them into a strong "Defender" case donated by Otterbox Ireland and send them on to a new home.

There is a lot of people who can benefit from an iPhone, but really cannot afford them.

iPhones come with expensive contracts and it can be hard for some parents to even imagine that their child could use such a thing, until they have seen it for themselves.

Some like Gracie are non-speaking and could use it to communicate more independently with an App. But there are others, like Murray, who can speak and be understood, but need support in the community. Murray has autism too, and attends a special school about a mile away from his house. When he turned 16 he held his mum to a promise to let him walk home from school. As a result of having an Autism Assistance dog, Murray has very good road sense and can navigate his way independently to and from the local park. But this was a risk for him - as the dog cannot spend the day at school - he would have to do this on his own.

Murray's mum decided to take a leap of faith and let him do it, but spent each day waiting and worrying - from the time school finished until the moment when she would see him turn the corner into their cul-de-sac.

I suggested that she set up Find My iPhone on her phone and watch him make his way home. She could text or call if he was taking too long, and teach him to text her back to reassure her. All she needed was an iPhone for Murray. I put him on my 'waiting list' for a donated device.

When Gracie lost her iPhone, I never imagined it would turn out this way. It was found (under a quilt in the soft play room in school) but she now has an identical spare and last Monday, I set up the second donated device for Murray and showed his mum how to watch where he is on the real-time map. He is already sending texts to his mum and she has the peace of mind of knowing where he is.

Find My iPhone allows you to send a loud signal to the device regardless of whether it is on silent or the user is wearing headphones. Very useful if your child goes out of your sight in a crowded place and you need to find them quickly.

Will any old iPhone do?

The phones don't have to be perfect - they just need to be working, and able to load iOS6 or above.

Many of the devices come in with cracked screens which are easily repaired. Murray's phone has a dodgy home button, but he is well able to manage it and I've got one with a broken power button that will be used for self-care reminders by a teenager who can plug it in himself each night.

They will be wiped and restored to factory settings, then placed in a shockproof/waterproof and a life-proof cover donated by my friends at Otterbox before going out to their new home.

So please don't feel guilty for lusting after that new iPhone 6 or 6+ - your 'boring' old iPhone 5, 5s, 5c, 4, 4s or even your lovely chunky 3GS can do a very good turn for someone who will really benefit from it.

It could open up a whole new world of independence and security for someone with autism and special needs. Now wouldn't that feel good?

Tomorrow, April 2nd, is World Ausitsm Day. To find out more about what events are taking place go here.

Lisa Domican is a mother-of-two and co-creator of the Grace App.