I presume by "putting on a deal" you mean buying membership?
You must have an active membership for services to work while roaming.
Even though the membership bundled allowances don't cover calls and texts while roaming abroad.
In the US you still also need cash credit on your account to cover the costs of outgoing and incoming calls and outgoing texts.
The costs are listed here:
http://48months.ie/membership-plans/going-abroadData is not supported while abroad so you need to use WiFi where available.
If you have an iPhone you need to be aware of this issue:
http://community.48months.ie/t5/Need-Help/Eu-roaming/m-p/36211#M13939Hope this helps.