New TTfone + UK 02 sim card can't make or receive calls in Eire

[Layman]

Hello there,

The details:

- TTFone is the phone brand name;
- Sim card bought new off eBay UK; 

Both items shipped to the Republic of Ireland.

- I added £10 credit remotely from UK, where I live, and got a confirmation email from 02.
- 'Phone is physically in Eire (Republic of Ireland), as a gift for an elderly person (whose land line went dead and it's taking a while to fix,) so this was a quick emergency option and is now proving to be a hassle.

Problem:
The phone can't make or receive calls.
The phone can receive texts Ok.

Solutions already tried:
Re-inserting the sim card;
Manually selecting the network.

Any ideas gratefully received.

[pgn]

Sounds like a Pay As You Go SIM - note this will not give you 5G connectivity, not yet supported by O2 on PAYG.

Try switching your phone down from 4G to 3G and manually rescan for networks and try to get one that you can use (Meteor, 3IRL, Vodafone IRL, even try those coming up as Forbidden) @Layman.

You did buy a phone SIM and not a Data SIM, I hope?

Check Roaming is switched on also.

[Layman]

Thank you for taking the trouble to give such a detailed reply. Appreciated. I will convey this to the phone owner.