4 hours ago
2 hours ago - last edited 2 hours ago
This doesn't seem to have anything to do with roaming in spite of the thread title?
The voice calls add-on is no use here and there was no point in buying it.
If it's a Northern Ireland landline then you can call it using the 048 prefix and it will be covered by your membership plan call minutes allowance.
If it's a mobile and/or you have to call it using the +44 UK prefix then it's an international call and you'll need an active membership plan and cash credit on your account to pay for the international call.
See here:
The massage that 48 gives when international calls fail because you don't have cash credit to pay for them is a bit confusing/misleading.
If you need to contact 48 support about this then see the links in my signature below.