Calls have increased almost 60% since the freecall number launched
The Samaritans charity has answered 1.2 million calls for help in the last two years.
A partnership with BT Ireland, eir, Virgin Media , Vodafone, Sky Ireland and Three through the Telecommunications and Internet Federation (TIF) made it possible for the group to launch a free to call number in 2014.
The industry has now committed to continue its support for the helpline until 2019.
The charity believes that removing the cost barrier has made it easier for people to access support, as they no longer have to worry about call charges.
It says calls to the helpline have increased by almost 60% since the freecall number was launched - and the charity is now answering over 1,600 calls for help a day.
Catherine Brogan is executive director at Samaritans Ireland.
"Everyone has moments in their life where they struggle to cope and for some this can lead to feeling hopeless and losing sight of being able to work through their problems", she said.
"We know that talking can really help people to see a way through and we would encourage anyone who is struggling to call Samaritans".
She says the free service has made a huge difference to the support they can offer.
Psychologist Niamh Fitzpatrick says she is also seeing an increase in demand from clients, and certain issues are dominating.
The Samaritans were awarded the number 116 123 as part of an EU initiative to provide a standardised number for support helplines in all member states.
A requirement of operating the number was that it must be free to callers.
And in September 2015, it also became free to call The Samaritans in Northern Ireland and the United Kingdom - meaning that anyone on the island of Ireland can call at no cost.
For immediate support call Samaritans' 24-hour helpline on 116 123, or e-mail firstname.lastname@example.org