Hi Decky.
Assuming that youm used a PC to post this request and assuming that you have Broadband on that PC then I would say forget using the BT Landline to make the call to the Republic of Ireland.
Dowload & install a program called Skype on your PC from the website: www.skype.com
Get a set of Headphones & Microphone for £1 from a shop called "Poundland" put some credit (£10) on Skype using your credit or debit card over a totally secure link, this would keep you going for a L O N G time, then you can call a lot of places far cheaper than using your landline using an option in Skype called "Call Phones".
You can also talk to any of your friends who have got Skype installed on their PC for FREE.
A "Call Phones" call to Republic of Ireland will cost you £0.012/Minute.
Sadly BT is a heck of a lot more expensive.
Calls to a whole raft of countries on Skype are only £0.012/Minute, however I regularly talk to friends in China, USA, France, Germany & Brazil who have Skype installed and it doesn't cost me a bean.
Good luck.