Three

Love taking these SIM cards abroad as it allows for the use of internet without having to buy a local SIM, just be sure to activate it in the UK before you fly and keep it in your phone, otherwise you will lose internet connectivity! Found out the hard way when I placed it into a travel router and realised my mistake.Even when purchasing the 10GB pack, roaming will still give you the 12GB limit so the data allowance is very generous, provided you are not abroad for very long or are not consuming heavy amounts of data via streaming etc.At around 8-10 quid per SIM (depending if you buy it on a deal) these are a nice cheap alternative to roaming abroad or even some local SIMs in some countries, the fact it works in 71 countries is great as it would cover most popular holiday destinations for most people! Only downside is, you will not be able to make local calls in said countries if you need that functionality. But you can call & text UK numbers no problem.

Perfect for travelling. Bought for going to the US as didn't want to pay for an extortionate bolt on or overseas charges. I have a dual sim so was easy to swap. No issues at all using in US and was perfect amount of data.

- Bought the sim card a few days before my trip to the US. Inserted it into my phone to activate it. Got the text messages with the number and everything, even downloaded the app.- Data seemed to work within the UK. However, zero balance was showing on my account (after registering the number, of course).- Contacted customer support, which confirmed that if my data is working in the UK, even though the balance is zero, it should work in Go Roam countries like the US (where I was planning to go and the reason for this purchase).- Went to the US. Data wasn't working (even though it is a Go Roam destination). Kept receiving notifications from AT&T or Verizon about how there is no data available and they can help me top up.- No data throughout the whole trip. Customer support informed that should I need data, I would need to top up. My explanation was that, since this is a pre-loaded SIM card and whatnot, I shouldn't have to buy more.- 6 days after contacting customer support again while in the US and sending them proof of this purchase, all I got was the following in an email:"Thank you for contacting us and sending us the proof as requested.We have attached the proof on the account."Needless to say, I still had no data for the remainder of my trip.It was my fault that I didn't heed the warnings of some other reviews on this page. I rarely leave reviews on products, but this time I felt that people need a heads-up should they decide to purchase this and essentially test their luck. I believe you would be better off purchasing a SIM from a different carrier that, even though it may be more expensive, would give you the peace of mind you deserve.

I've used these sims several times, without problem, just make sure you activate the sim in the UK before you leave an make a call or send a text message (or both to be sure!). Don't forget to change settings for apps like Spotify if you normally download over cellular, (those auto update playlists will quickly eat your data!)Worked perfectly in USA and BrazilHowever, be aware of third party sellers, I purchased my latest card thinking it was from Amazon, only it wasn't Amazon it was a third party fulfilled by Amazon, rather than getting a preloaded data sim, you get a sim with no mention of data, and a sticker on the back to call, text or WhatsApp to get your credit, the data never arrived and Amazon refunded me, luckily I had time to reorder. If you get the card pictured you are good to go, anything else I wouldn't trust it, as if you get abroad to find it doesn't work it will be costly to use data.

I was very concerned about my family running up a huge phone bill on a recent trip to New York so we removed our UK sim cards and used these instead. These sims allowed for worry-free calls and texts on the trip although a message occasionally popped up saying there were insufficient funds on the card to make the call. The same message then did not appear on other occasions. WhatsApp using the sim card's data became the most reliable way of keeping in touch during the trip rather than the mobile service itself if that's make sense. Used Google maps constantly to get around the city and only used a fraction of the data.

The Three Mobile PAYG Voice SIM Pack is excellent! With 10GB for just £10, it's fantastic value for money. The setup was quick and easy, and the network coverage is reliable. I'm very pleased with the performance and affordability. Highly recommend for anyone needing a budget-friendly mobile plan!

Far cheaper than paying the add-on fees to roam abroad.

Tested in San Francisco and Los Angeles. Works well and speeds are quite good too, 50-80MB download. All you have to do is insert it into your phone and enable roaming in the settings. These work in Ireland and UK too.Three offers two similar SIM cards on Amazon, I did not know which was better so I bought both. They are the same, speeds are the same. You don't have to register them, but if you want to find out how much data you have left, you have to. Registration process was not really straightforward for either. The 12GB was harder to register, I had to dig around in the Three's site but once registered the website for it is more updated.The only part I did not like about these SIM was that Hotspot functionality is disabled on them. You can't share your Internet with the others.