Mobile network eir has said the root cause of a problem that was causing a outage on their network has been identified and service to customers has been restored.

It says the issue impacted all of its mobile customers.

In a statement on its website earlier, eir said the problem was affecting customers when making calls.

The telecom company thanked customers for their patience and apologised for the inconvenience.

The company said data services had not been impacted by the outage.

On Twitter, angry customers geographically spread across the country were reporting they could not make calls with the problem beginning earlier today.

A spokesman said the issue was not the result of a hacking incident.