Customers in the midlands say they are not able to make or receive calls.
Three Ireland says it is working to resolve an issue with its network this morning.
Users say they are not able to make or receive calls.
Customers in Mullingar, Athlone, Tullamore, Edenderry and Portlaoise have reported issues.
It has apologised for any inconvenience and hope it will be rectified as soon as possible.