Do I need an unlocked iPhone when returning to the UK?
I have the 4s and was planning to upgrade anyway. AT&T is my present carrier. They were able to sort me out for various trips (Australia, Russia, Sweden and the UK) in the past. I think I read somewhere I need a phone that has a specific exchangeable SIM card? Has anyone experience with this? It is so much cheaper to purchase the phone here before I leave.

You will need to get it unlocked so that you can use it on another network. If it isnt unlocked then you can only use it on AT&T. All i-phones are GSM which is what is needed for it to work in the UK and europe. You will just need to buy a new simcard from a UK wireless provider when you get to the UK.

I bought my iPhone 5 from Apple before I left the US. I went with Virgin for a SIM only plan as they are dead cheap - £15/mth unlimited text, talk and data - but if you want 4G you'll need to go with 3 or EE I believe. I don't know about the new 5s but not all of the earlier ones were 4G compatible in the UK so that is something to ask about. I've been quite happy with 3G and Wi-Fi on mine.

It is much cheaper to buy the phone and then get a SIM only plan than get the phone on a 2 year contract.

Oh my gosh......so inexpensive compared to here :-)

Yes - they are much cheaper in the UK. Most of my friends back in the UK have Iphones or other Smart phones. When they told me what they pay I couldn't believe it. I cannot afford one here - I just have a simple phone for talking & texting (no internet).

wow it really is cheaper I pay $65 a month for unlimited services in the US. Another thing to add to my list of positives for moving back to the UK. The phones themselves seem to be cheaper over here so upgrade before you go.

I pay $103.00 for phone, texts and limited internet. Never use internet. Use my iPad for that. Texts hardly. Downloaded Viber........free phone and texts everywhere in the world for free. Phone calls iffy.....but texts plus pics excellent FOR FREE......it's brilliant. My whole family uses it....

Some US iPhones 5 (5, 5c and 5s) operate on a different LTE (4G) band than UK LTE providers, such that if you bring an AT&T iPhone 5 to the UK you'll get 3G service, not LTE. Verizon phones, while CDMA, do have GSM capabilities and are, by law, required not to lock the SIM card capacity. Some Verizon iPhones operate on the same LTE bands as UK providers, I think.

http://www.apple.com/iphone/LTE/

Also worth noting that "on paper" the iPhone warrant is country-specific, not worldwide. There are dozens of reports of people getting warranties honored in other countries, but there also reports of people being turned down for service when bringing in a third-country iPhone for repair.

Basically, seriously consider upgrading if you are moving over permanently. Sell your old phone on ebay and use the cash to upgrade when you arrive.

Holy moley! I never thought of that! That's the next problem DAMMIT!

(Celtic-it's clear you are having a rough time, all good wishes to you )

I was lucky enough to buy one in a batch that is LTE compatible but as I am with Virgin and don't live in an area with coverage, it doesn't matter to me. LTE (4G here) is only available in certain areas and it's a much more expensive plan through EE. If you go to their website you can see where it's available.

I paid $702.29 incl tax for mine and the 5c is £469 which is about $750 at today's exchange rate and the 5s is £549 - $878 at today's rate. If you don't need it before you leave the US, you might consider paying the extra and buying it in the UK. If you keep the phone for 2 years, the 5s is only an extra $7.33/mth if you average the difference out over 24 months. I wanted mine before I left the US for various reasons, including the iBookshelf app. I have a lot of books and wanted to keep track of where they were packed so I could get at one if I need it.

I use my iPhone as a hot spot for my iPad (which I did buy here) if I need to. I have to have an iPad for the software the company I do work for uses and most of the customers I go to have wifi so I didn't feel the need to spend the extra £100 for a cellular capable iPad plus another data plan. Virgin told me they don't support tethering. That doesn't mean you can't do it though! They told me they would write to me if they saw my data plan go over a certain limit but that hasn't happened and if they get upset about it, I can switch to 3 as I'm on a month to month. 3 has a month to month plan for £18 with unlimited data, 2000 minutes and 5000 texts. You can do the same plan for £12 if you sign up for a 12 month contract.

That may be more information than you need (and I have more about how to get the nano sim from Virgin if you decide to go that route) but setting up the phone takes time and research depending on what you want/need.

I went to the Apple store in Bluewater to buy my iPad and I couldn't have had better service. The guy who helped me saved me ££ that I would have spent if I'd bought online - i.e. using my phone as the hotspot, buying 16 GB and signing up for iTunes match instead of buying 64GB. I ended up spending £399 instead of £649.

Slightly OT, but I have a 3G phone that can actually access a 3G signal maybe 5% of the time, tops (that includes when I am at work, in the middle of a large city). When there's no 3G signal it switches to the regular (slower) signal, but I wouldn't buy a 4G phone at the moment.

It may be worth trying to get an idea of the extent of 4G coverage where you plan to live. Of course if you plan to buy a 4G phone anyway, the suggestion is moot.

Will ATT unlock the iPhone for you or do you have to take it to apple. I have the same service provider so I'm assuming I will have to end my contract with them before I move to the UK, then get a new SIM card

AT&T will be able to tell you how to unlock the phone, but they will not give you the code unless the phone is owned by you outright (not on a payment plan) or until you have paid anything you may owe if you cancel your contract early.

Thanks for the tip on Viber. I have been trying to get Whatsapp to work and not having much success, so I am going to try Viber.

My iPhone has a Pay as you go O2 sim in it and works great.