The company says a suitable buyer was not found
Virtual mobile network iD Ireland has been placed into provisional liquidation.
The network was created in 2015 by Carphone Warehouse Ireland Mobile -a division of Dixons Carphone.
Dixons Carphone says it invested "substantial resources" to establish iD Mobile, and has continued to support the business financially.
But in a statement it says: "Despite a compelling consumer mobile proposition in an increasingly competitive mobile market, iD Mobile was unable to achieve scale against established operators and its losses became unsustainable.
"Interest from several potential buyers of the business was explored over a period of more than 12 months.
"However, a suitable buyer with the resources required to make the MVNO a success could not be found and reluctantly a decision was taken to close iD Mobile in Ireland."
It says the key focus is now on ensuring iD Mobile's 40,000 customers can transition over to a new network with minimum disruption and inconvenience.
Dixons Carphone has successfully applied for the appointment of a provisional liquidator to allow full service to be maintained for all iD Mobile customers while they transition to an alternative network.
iD Mobile says its suppliers will also continue to be paid for services they provide during this time.
Customers will be contacted by text, letter and email in the coming days, and will be offered full service on the iD Mobile network for the next 30 days.
Bill-pay customers will not receive any further bills, and pay-as-you-go customers will be able to use any remaining call credit over this period.
"iD Mobile customers are free to move to an alternative network as soon as they are ready", the network says.
Customers can visit their nearest Carphone Warehouse store or website for further information.
Mark Delaney, managing director of Dixons Carphone Ireland, says: "Having explored all the options available, we have reluctantly taken the decision to close the iD Mobile network in Ireland.
"To safeguard against any loss of service for our customers in the coming month, we are providing significant funding to continue paying suppliers for their services during this time.
"Helping our customers to seamlessly transfer over to an alternative network with minimum of disruption is our key priority.
"From today, our expert team at any of Carphone Warehouse's 82 stores nationwide is available to move customers to an alternative network and assist them in choosing an operator that meets their specific needs".