If ringing from outside the University then prefix the extension number as followsz:
2000 to 2999 use prefix +353 61 20
3000 to 3199 use prefix +353 61 21
3300 to 3599 use prefix +353 61 21
3200 to 3299 use prefix +353 61 23
3600 to 3799 use prefix +353 61 23
4100 to 4299 use prefix +353 61 23
7000 to 7999 use prefix +353 61 23