See below for a list of suitable software to use with Irish VoIP numbers. Note Irish VoIP numbers can also be used with a Cloud PBX to make and receive calls.
Irish VoIP Android app https://play.google.com/store/apps/details?id=com.irishvoip.phone
Bria Mobile (Most Recommended as it works for Push Messaging in background)
Microsip (Most Recommended) http://www.microsip.org/
For details on how to configure your number for use with FreePBX see below