I can't really help with the UK sim card (sorry!) But I can tell you what I do. I use T-Mobile as my carrier. Their unlimited plan for those aged 55+ is only $70/month for two lines (I caught the tail end of a commercial last night that said for a limited time it's only $55, so I have to investigate) The great thing is that in addition to unlimited data and text while I'm in the US, T-mobile also gives me unlimited data while I'm abroad (they only guarantee 2 G speeds, but I usually get 3G or 4G) and uimited texting to/from US phone numbers.

It's also great because I can use Google Maps and other apps without worrying about using up data.

Viber Out" credit. With Viber calls are only about 2¢ per minute. Since I have free data I can use Viber even when I don't have wifi.

It's also great because I can use Google Maps and other apps without worrying about using up data.

This has worked great for me on my yearly 5-6 week treks across Spain.

Oh yeah, I also use WhatsApp quite a bit.

Is WhatsApp preferable to Skype?

Whatsapp is owned by facebook and has had some security issues. I have not used it so I'm not well versed but it should be easy to investigate.

This may be helpful. https://startupstash.com/whatsapp-alternatives/ We use Signal.

I have never used Skype. Everyone I know in Europe uses WhatsApp, which will work with data and/or WiFi.

I use whatsapp all the time to the uk. You can text, video calls and phone calls are all great. Facebook messenger is equally good. Your contacts, obviously need to do same. Just download the app.

I am actually surprised how little whatsspp is used in the US, probably because everyone has text.

The Orange Holiday SIM allows you fixed minutes and calls from UK and Europe to any worldwide location. You can use your dataplan instead, if supported, to use Skype or Whatsup to save minutes.

WiFi calling allows you to place and receive calls using the WiFi network when you are in your hotel/rental. BTW, it will also work with a US phone carrier plan even if you have the cell phone calling (roaming) turned off.

I don’t know what Orange SIM card my daughter had (she bought hers directly from an Orange store in Madrid) but it was valid for 30 days and had plenty of minutes on it. I just linked that Holiday one b/c it can be purchased in advance. my daughter called home at least once a week via WhatsApp - our phone calls were anywhere from 30-60 minutes each week. Since she was there for four months, she had to “top off“ her card every month-she could either go online and do it, or just go back to the store. She lived a couple blocks from the store so just did it there at a kiosk. I dont know how long IdaClaire plans to be gone but I’m assuming she will be able to find a SIM card that has enough data for her to make whatever necessary calls home while she’s traveling. I’m guessing my teenage daughter was probably using way more data (hello Snapchat, you datasuck) while out and about than IdaClaire probably will be.

it was much cheaper for our daughter to replace her SIM card than to keep her on our Verizon plan, which was $10/day for international travel. Her Orange SIM card was around $25/month.

WhatsApp doesn't completely replace Skype (or in my case Viber) because the other party needs to also have WhatsApp installed on their phone. If you need to call a landline or someone without WhatsApp, you would use Skype, Viber, etc.

We used WhatsApp a few times and it was great.

I called our service provider (Verizon) and got the details of what would be the best plan for us in Ireland and Scotland last fall. It turned out we could have unlimited talk and text and could activate a phone via a single phone call back to the states for $10/day (We never did that and used WhatsApp). We have iPhones, no SIM card. Check and see, but with your Samsung, you might indeed be better off using a SIM card.

When I was in the UK last August-September, I got a Vodafone SIM for £10 As I recall, the rate was for 30 days. There was enough data and unlimited calls within the EU. Things might be different now with Brexit. I didn't have enough time to get the SIM mailed to me, so I picked it up in a Vodafone store. The good part of that is the the salesperson installed and checked that the SIM was working before I left the store. You have to use a credit card for purchases; they don't accept cash. I was there for a week and had lots of data left, but the cost for using that in the US was horribly high.

outsidePlaying, iPhones use SIM cards also.

You can also rent a traveler's mobile wifi hotspot that you just carry around with you to stay on wifi everywhere you go. It's usually a pocket size thing that you re-charge overnight, and some will run up to 10 devices at once. I've used these with great success in Europe, and (for me) they're far more convenient than anything else. Each one has its own password, so it's more private than hotel or public wifi.

There are several companies that offer these in the UK. One with which I have great experiences, and so would highly recommend them is Travelers WiFi. They have pickup right at Heathrow, or other delivery options if you prefer. Return is by dropping the unit in a pre-paid return envelope as you leave.

Here's a link to one site in case you're interested: Travelers WiFi

3katz, well, yes they do of course, I misspoke, but they are not as interchangeable as some other phone SIM cards. It’s easier to just use a data plan I find.

A relative just returned from an overseas trip. They have an old iPhone 6 with Verizon. They bought a cheap SIM card (I think it was a 3 gig card) as did everyone they were traveling with (5 in total) and used them for 7 days for data and a few local calls. Everyone used WhatsApp unless it was a local call for a taxi etc. I spoke with or video talked several times a day and often for 45 minutes to an hour at a time and they didn't run out of data till they were literal boarding the plane.

Last time I travel to London I just used the Verzion $10 a day plan. Never again, I'm buying a SIM card either before hand or in the airport.

Let's start with network protocols. Europe uses GSM. Many US carriers (e.g., Verizon) use CDMA. GSM phones always use SIM (subscriber identity module) cards. If your US phone is LTE-capable, it has a SIM card. Basically, newer mobile phones have a SIM card. Since you said that your phone is unlocked, that implies that the phone may work with SIM cards from other carriers.

Your phone should have come with a SIM card ejector. The one for my iPhone looks a bit like a tiny, thin paper clip that has been bent to have a tail.

Carriers use different ranges of frequencies. Your phone needs to support the range used by the UK carrier you choose. iPhones support most frequencies. I suggest checking to see what frequencies your Samsung model supports.

Here's a link where you can check to see if your specific brand, model and sub-model will work in the target country with various carriers in that country. Will My Phone Work

Thanks so much for all of the input and suggestions! Moxie, I particularly found your link helpful, as I might not have even thought about checking to see which carriers support my phone. (Turns out, a good number of them do across all bands, including names I recognize like 3, GiffGaff, O2, and Vodafone.)

We used a portable WiFi in Iceland and it was a godsend. I think a UK SIM card will be the more economical route to go for my trip, though, so will continue to pursue that route.

Looks like several of you successfully use WhatsApp. I'm probably more likely to continue using Skype, as I don't use Facebook products at all if I can avoid it (just a personal thing with me, no need to expound on it here). In thinking this through, I'm hesitant to ask my US contacts to download an app if they don't already have it.

Actually, I may need to explore switching my carrier (particularly if I can find one that includes talk/text between UK and US), and perhaps looking at getting DH and I on the same plan. My phone was not unlocked until recently, so this wasn't an option - but it is now.

If, however, I keep my current carrier (which does not have coverage in the UK) and purchase a UK SIM from one of the carriers that is compatible with my phone, I remain confused as to how calls and texts between the UK and US work. I understand there's a charge associated, but how do I pay for the calls and texts?

ETA: Looks like with some SIM cards, the cost of texts/calls from UK to US simply comes out of airtime credit and can be topped up online as needed.

If you are thinking about switching carriers, in addition to T-Mobile, Google Fi is a good option for travelers. Data costs are the same when traveling abroad as in the US. However, the types of phones that work with it are more limited. Also,Sprint has a plan similar to T-Mobile with free texting and basic data internationally.

Thanks, Terriks! I'll explore this a bit further, but am probably leaning towards keeping my current carrier and just getting the UK SIM card for short-term use. I've actually ordered the free SIM from Giffgaff, as they allow you to select your plan and credits after you receive the card. I can't envision any further international travel in the near future beyond this trip, so I think I may be making too big of an issue for this relatively short trip that's upcoming (but hey, that's what I do ;-)).

T-mobile works without any switching in the UK between US and UK. Not sure on the charges at all since I have since switched and it likely has changed since then. I remember it texting me with the costs as soon as I landed. However when we were in the Carribean we got the same text and it was free. This was a few years later.

AT&T works too and you can go and select an addition to your regular plan that varies in cost in how you expect to use it. You go online and select it and it is only for a certain time period so you don't continue to pay for it. For example I selected a unlimited data with no phone/text use for $20 when I traveled to Taiwan recently and it had a certain number of minutes for calling, but I knew i would use the hotel WiFi mostly so and have WiFi calling support so didn't feel the need to have more than a little in case of emergency and being out on the town, but wanted data for maps etc. This charge is only added from the first time you use it and I never needed it so I was never charged. I stayed on airplane mode with WiFi turned on the whole time. Called and texted with my family with no issues doing that.

BTW neither of these need a sim card change.