It should work if you're on a Guido membership.
If you're not on a Guido membership then calls/texts/data will NOT work.
Note that some people roaming in the EU on a Guido membership have had problems getting data to work.
If this happens check what the APN field of the APN is and if it's not 48months.liffeytelecom.com then change it to that and toggle airplane mode on and then off and try again.
Hope this helps.