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20 common questions about SIM cards

If you’re obsessed with tech like us you’ll have bagged yourself a new iPhone several times over the years. And each time you’ll have probably transferred your SIM card from cherished iPhone to cherished iPhone without a care in the world. But have you ever stopped to think about the tiny electronic marvel you’re holding in your fingers? Well, wonder no longer! We’ve got answers to pretty much any question you could ask about these far-from-humble components.

But while your SIM card sits safely inside your latest purchase, the iPhone itself is still very vulnerable to theft, loss, breakdown or damage. Call the helpful Gadget Cover team and make sure you have the most up-to-date iPhone insurance cover to suit your needs and budget.

  1. What does SIM mean?

Let’s get the most basic question out of the way first! SIM is an abbreviation for Subscriber Identity Module or Subscriber Identification Module – depending on who you ask. The first credit card-sized SIM card was developed way back in 1991 by German banknote and smart-card specialist Giesecke & Devrient. These early models could only store up to five messages and 20 contacts. According to a recent study by Ericsson there are now more active SIM cards than people on Earth!

Sim card with phone

  1. How do SIM cards work?

As its name suggests a SIM card holds the information required to identify individual users and to connect devices to the global communications system. It fits inside your smartphone or tablet and acts as your device’s unique ID. This lets you make and receive calls, messages, browse the internet, access 3G, 4G or 5G or download apps – all depending on what your contract allows. For such a small part, it’s got a big job to do!

  1. Are all SIM cards the same?

No, the circuits within SIM cards have evolved over the years as the different ‘generations’ of cellular technologies have been launched. So, if you have an old SIM card that worked with 3G, but you now want to access 5G then you’ll need to swap it out.

  1. What are the different sizes of SIM cards?

If you’ve ever swapped a SIM card between phones then you’ll probably be aware that not all phones need SIM cards of the same size. In fact, there are three different sizes in use, namely Standard (25x15mm), Micro (15x12mm) and Nano (12.3x8.8mm). The only difference is the size of the border around the chip, which allows the SIM to fit into different models of phones.

Which one you'll need depends on your model of phone. If you’ve held onto your iPhone 3G then you’ll need a Standard-SIM, the iPhone 4 needs a Micro-SIM while the iPhone 5 and above needs a Nano-SIM. Pretty much all modern smartphones now use the Nano-SIM as manufacturers have sought to create ever smaller and lighter devices.

  1. Can I cut down a SIM card to fit my phone?

Yes, you can. That bit of plastic surrounding the golden ‘chip’ has no impact on how the SIM works. Many stores have so-called ‘SIM cutters’ to cut down SIMs that are too big. However, we don’t recommend you do it yourself. You can completely ruin your SIM if you make a slip. Considering how important the SIM is to your phone’s operation it really isn’t worth the risk.

  1. How to insert a new SIM card into an iPhone or newer Android phone?

Follow this step-by-step guide:

  • Power off your phone.
  • Remove any phone case, holder or other accessories.
  • Find the SIM card tray on your phone. For iPhones this is on the right side of the phone (the iPhone 12 generation has it on the left side). For Android phones this could be on either side or the top edge.
  • Pop the tray out by inserting the SIM removal tool into the small hole on the tray. If you have lost this then use the end of a paperclip.
  • Remove the tray but remember which direction it goes back in!
  • Remove the old SIM if there is one.
  • Set the SIM card into the correct sized notch in the tray.
  • Slide the SIM tray back into the phone. The tray will only fit one way. Never force it.
  • Turn on your phone and you’re done!

If you’ve got an older model of Android smartphone, the SIM card compartment is located under the battery in the back of the phone. You'll have to remove the back cover and battery before inserting the SIM card.

Always make sure you have iPhone insurance in place to guard against any accidents.

  1. What way up does a SIM card go in?

When dropping your new SIM card into the tray, there is a further issue to be aware of. Depending on the model of smartphone you might need to place the SIM with the gold contacts face up or face down. Some smartphones include a helpful diagram to let you know. If not, you’ll need to refer to your user manual or ask in store.

  1. Do I need to activate my new SIM card?

If it’s a new phone with a new SIM then you’ll just need to insert the SIM card and you’re done (after a couple of minutes wait, that is). However, in other cases you’ll probably need to activate your SIM. This procedure can be a bit different depending on what provider you’re with. They should tell you what to do.

  1. Will my phone work without a SIM card?

The short answer is yes. A smartphone will ‘work’ without a SIM card, but only for certain tasks. Provided you’ve got access to Wi-Fi (at home or in a café for example) then you’ll still be able to get on the internet, play music, send emails, upload cat pictures to Instagram, etc. You won’t have a phone number and the same ability to make and receive calls, send texts or use data when out and about but there’s still a surprising amount you can do with these marvellous machines.

  1. What information is stored on a SIM card?

As well as the ability to store contacts, phone numbers and text messages (up to a certain amount) your SIM also holds some vital information. This includes the International Mobile Subscriber Identity number which allows the network to identify your device, and the Authentication Key that identifies you as the authorised user.

  1. Can I find my mobile number using my SIM card?

There are lots of times when we might need a reminder of our phone number. Particularly if we’ve recently switched networks. Here are four simple ways to get your number using your SIM.

  • Use a special code – Every UK network provider offers a free special code service. Simply call or send a text, and your number will appear on your display.
  • Check phone settings - On Android go to Settings > About phone > Status/phone identity > My phone number. For Apple go to Settings > Phone > My Number.
  • Check your SIM card or its packaging – Your number will appear here.
  • Look in your numbers – Open the Contacts app and scroll to the top. Your number will usually be displayed under My Card or My Number.

If you’re in the market for a new provider then check out our guide to the pros and cons of SIM-only contracts.

  1. How much data can I store on my SIM card?

Not much. Despite them being a similar physical size to one of those multi-gigabyte memory cards, SIM cards have a far smaller storage capacity. Most range between 32 to 256KB – so pretty tiny in today’s terms. It’s still enough to store most of your contacts and texts but nowhere near enough for music, photos and videos! That’s why your phone’s internal storage and the Cloud are so important.

Inserting SIM card

  1. My SIM card Is full. What do I do?

Space is limited on a SIM card so it can get full. Try deleting any unnecessary text messages or contacts you no longer need. You could also ask your provider to send you a new one with a larger storage capacity.

  1. Can I use my SIM card in another phone?

Provided the two phones are with the same provider or the other phone is ‘unlocked’ then there’s no problem moving your SIM around. You’ll keep your number and any data stored on the SIM. The only difficulty is if the two phones require different sized SIM cards. You might need to get the SIM card cut down or use a SIM expander.

  1. Can my phone be tracked using the SIM card?

In these security conscious times this is an important question. The answer is technically yes, but someone needs a great deal of serious tech to do so! As explained previously, SIM cards have a unique serial number that is transmitted to nearby cell towers to ensure that you get the strongest signal. Phone companies, providers and the police can, in theory, use this to narrow down your location.

  1. My phone keeps saying ‘No SIM’ or ‘No Sim Card Detected’. What do I do?

These error messages can be irritating and can be caused by various things including manufacturing defects, physical damage to the SIM card or misalignment of the SIM card. Follow these troubleshooting steps.

  • Check you have an active plan with your network provider.
  • Check your phone’s OS is up to date.
  • Restart your phone.
  • Take the SIM card out and put it back in. Double check positioning of the SIM card, make sure the tray closes properly and isn’t loose.
  • Try the SIM in another phone.
  • Try using another SIM card if you have one. If you don’t have one then go to a retail store and ask them to test with another SIM. You might need a replacement.
  1. Are SIM cards secure?

Just like any part of your smartphone, SIM cards can be open to attack from cyber criminals after your data. You can set up a security PIN to stop someone else from using your SIM in another phone. On an iPhone, you change the SIM Card PIN under Settings > Cellular > SIM PIN. On an Android, select Settings > Security > Set up SIM Card lock.

  1. I’m going to Europe on holiday. Will my SIM card still work?

Unfortunately, the guarantee of free mobile roaming within Europe ended when the UK left the European Union. Your SIM will still work but you might have to pay for the privilege. Always check with your provider before you travel.

  1. Are SIM cards waterproof?

If you do happen to go on holiday then sometimes accidents involving spilt drinks or swimming pools can occur! While the SIM card itself is waterproof the phone itself probably isn’t. Many new iPhones offer excellent water resistance meaning they could survive a certain level of immersion, but please don’t test it out.

If your iPhone does get damaged due to splashes or even full immersion then iPhone insurance policyholders could get their beloved iPhone repaired or replaced.

  1. How do I destroy a SIM card?

SIM cards can contain a lot of personal information, so if you get a new one then you’ll want to make absolutely sure the old one doesn’t fall into the wrong hands. All you need is a pair of scissors! Simply cut across the golden ‘chip’ to render it useless. To be safe, cut it into small chunks and in different directions.

Protect your new iPhone with Gadget Cover

Now we’ve answered all your possible SIM-related questions, do you have any ones about iPhone insurance? The team at Gadget Cover are always happy to provide an answer.

Our policies can offer protection against accidental damage, liquid damage, theft, breakdown and unauthorised usage as standard. And for an extra premium, your iPhone will be covered against loss, too.

Additional benefits include family cover to extend protection to your immediate family, worldwide cover to include use of your iPhone anywhere in the world, and e-Wallet cover up to £500.

Get a quote for iPhone insurance from Gadget Cover today.

Policy benefits, features and discounts offered may very between insurance schemes or cover selected and are subject to underwriting criteria. Information contained within this article is accurate at the time of publishing but may be subject to change.

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