Mobile phone/Sim card

Who is your carrier? I would contact them to see what they suggest. I have Verizon and I just upgraded my plan for the time I would be overseas for my iPhone 4s.

I have a friend who added an app to his Iphone 5s called Voxofon. I haven't tried it but he has called me and his whole family using the app. It is WiFi based and allows for free phone, text, picture, etc.

Trying to use a sim-card in an iPhone has some mixed results for US travelers. I had a friend take their 4s and it wouldn't work with a new sim-card until she was able to connect her iPhone to her iTunes account on a computer. Other people haven't had a problem but with that said I would check with your current provider on their international rates. Many have gotten much better and if you just plan to use it now-and-then or for emergencies this could be the best option. You can even use Skype or other internet phone app options to call hotels or restaurants within Ireland when you are connect to wifi (hotels or coffee shops) on your iPhone.

I know this thread is getting a little stale, but I guess I'll try chiming in. (I really can't believe how little info on this topic there is here. And that search function is worthless. I had to browse down the list to find this topic.)

Anyway, with an iPhone 5 you should have no problem buying a short term plan and popping in a Nano SIM card that enables it.

I've done it for my iPad Mini in France (20Euro though Orange - one month, 1G data), Germany (Vodaphone - one month, unlimited data upgrade for 24Euro), and Mexico City (the SIM and 1G of data were free in the DF since I caught a 'TelCel' promotional period!)

I've found most carriers to be competitive with their 'tourist package' pricing. And it's WAY cheaper than what Verizon is offering for data usage in Ireland ($25 for every 100 MB.) Since I now own a 'tablet' I've stopped buying maps, so if you're using Navigation on iMaps, you can go through nearly that much data usage in one day of serious driving.

For this upcoming trip to Ireland, I'm guessing I'll end up using '3' or 'Vodaphone IE'. The most important issue in choosing a provider is ease of finding a store right near the airport. (I don't know why they don't have kiosks inside the airports, but I've yet to find a company providing this convenience as yet.)

Unfortunately, I'm flying into Shannon, so here's where suggesting the most convenient mobile phone store won't work. But if someone who lives in Ireland want's to suggest an easy place with efficient staff--maybe an upcoming promotion on short-term plans--they know of for either airport, I'm sure we'd love to hear about it.

Thanks everyone. Since I have a couple of weeks left, I am checking into everyone's suggestions to see what works best for me. I did find out that changing the Sim Card on the new iPhone 5s is pretty simple (according to the guy at Verizon!!!) all you need is WiFi to activate the card, which I have at the hotel I am staying at.

************UPDATE**************
We just got back from our trip and I wanted to share my experience. After doing some research, I ended up taking my phone (iPhone 5s) to a Meteor store in Dublin, they popped a sim card into it and with 20 euros I had unlimited data (which came in handy for the GPS and Yelping) and 10 euros worth of calls which I just needed to book our B&Bs as we traveled. It was easy and cheap and I was able to Facetime my parents and friends from in the middle of no where. Just put my old sim card in when I got back. It's for sure the way to go if you want or need data.

Glad it worked out for you. It did so because the Verizon 5s is unlocked, meaning it can be used with any GSM band carrier in the world. The ATT 5s and T Mobile's 5s are locked to those carriers, however. T Mobile is willing to unlock the phone after 40 days, but ATT won't until the contract is up. Unlocked iPhones and other smartphones can be bought from a number of places including eBay and Amazon.

If people expect to have a problem with their cell phone /mobile phone then maybe this would be a better solution - just buy a phone from any of the networks and use it here.
This supermarket chain ( largest in Ireland ) TESCO http://www.tesco.ie/ , will sell you a phone+SIM for as little as €10, AND your calls back to the US can be as little as 2c/minute !!
http://www.tescomobile.ie/shop.aspx
http://www.tescomobile.ie/priceplans/international/index.aspx
When you buy the 'Pay as you go' phone you can top-up by €10 ( you usually need to get to a Tesco shop to 'top-up' your credit, but there's so many of them it shouldn't be a problem finding one in any town in Ireland !) , and get €10 credit for local calls / DATA. Other networks charge a lot more for calls to the US but you should choose what best suits your needs, or if you're travelling more in Europe / UK then o2 / Vodafone / 3 might suit you better ?

I brought my Verizon IPhone 5 on my recent trip to Ireland. I tried to purchase a nano SIM from Tesco Mobile for my IPhone, but alas, it did not work. The technician said something about Tesco Mobile being a virtual network and thus not compatible with this phone. However, the Meteor SIM he sold me for €10 unlimited data worked perfectly throughout my trip. Topped off with additional €s and my phone was set for Ireland. This saved my from having to buy a pay as you go phone and gave me mapping for my time in Ireland. The Google Maps app worked great throughout the country.