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How a SIM card works

I will be spending a couple of weeks in England/Scotland. I have an old flip phone that has been out of use that I want to use only to make connections with friends. I understand that I can get a SIM card at Heathrow and insert it. I presume I also have to buy some time as well, correct? Do I do that at the same place I get the SIM card? Do I get the phone activated by buying phone usage time? I've never done this before, so I'm clueless. Any help would be greatly appreciated.

Posted by
5687 posts

You'd be buying a "prepaid SIM." They are all a little different. But generally, you could just walk into a mobile shop and they will set it all up for you so the phone works when you walk out the door. You'll have a UK number, and you'll have some credit on the SIM for calling minutes.

However, don't assume any old flip phone that worked in the US will work in Europe, for a couple of reasons:

  1. The phone must be GSM-compatible. GSM is the mobile technology used in Europe. In the US, T-Mobile and AT&T also use GSM. Verizon and Sprint use a technology called CDMA which is completely different. If you have a Verizon or Sprint flip-phone, chances are it will not work at all in Europe.

  2. If you have a T-Mobile or AT&T phone that you bought it from them, it needs to be "unlocked" to work with a foreign SIM card. This means you have to obtain an "unlock code" from T-Mobile or AT&T and type in that code the first time you insert a new SIM card in the phone.

  3. Even then...some old flip phones, even the ones that are GSM, may not have the Euroepan GSM frequencies. My old T-Mobile flip phone from 2009 does not and will not work in Europe. An older flip phone does. Just depends on the make/model of the phone.

(And if you aren't from the US, then I have no idea what technology, GSM or otherwise, your phone might use. Depends what carrier it was used on!)

You'll probably find it better to get a cheap smart phone. Then you can use apps like WhatsApp to communicate with the locals - WhatsApp is popular there. Can't use it on a flip-phone. On a smart phone, with WiFi, it's free. And a smart phone is more likely to work on GSM in Europe.

Posted by
1075 posts

Personally I wouldn't buy a SIM card at an airport, there have been reports on travel forums that they are overpriced, don't work and no customer service from the vendor, better to buy one from a mobile phone shop like Carphone Warehouse.

Posted by
3124 posts

I agree with the advice to buy the SIM card from a shop outside the airport. Carphone Warehouse is one of the largest retailers in the UK, meaning that if you have trouble with your phone several days later, when you've moved on to another city, there will likely be a Carphone Warehouse shop not too far out of your way where you can go to get your problem solved.

Posted by
119 posts

I Agree with Andrew H, your old flip phone still may not work outside the US, does it have a USB cable? USB ports for charging electronic items are very common now, this will save you using a socket outlet plug adapter,

SIM card sizes can be different too, there is standard/nano/micro SIM.

You can buy a sim-free refurbed/preowned smartphone with 1 year uk warranty from around £100,
A Smartphone has the useful features for travelling like wi-if, maps, GPS, Bluetooth, apps, twitter, also the popular whatsApp was mentioned.