No. He can buy the EU roaming add ons if he wants.
You can call him as normal as if he was still here - i.e. you don't have to do anything special and calls to his mobile will be covered by your membership/add-on allowances.
Never buy EU roaming add-ons unless you are going abroad to the EU. It's of no use if you are staying put in Ireland.
If he buys the EU calls add on then he won't be charged anything from his credit balance to receive calls. If not then he will need cash credit to pay for these and maybe other services.
Hope this helps.