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What is a SIM card: How to cut your SIM into a micro-SIM

Typically, changing mobile networks is a little bit of a hassle. The main time sinks come as part of the transfer process from one SIM card to another. If you take out an entirely new SIM plan or phone on a new contract, chances are you’ll have to contact your old and new networks, ask to have your number transferred over and then sport two phones for the 24 hours that follow, not knowing which one will ring and which one is suitable to text and call out from. The problem is even more apparent if you change from an older handset onto a newer one, without changing network.

More and more handsets are opting for micro-SIM cards over the larger more typical SIM cards used by the majority of handsets over the past few years and the same waiting game has to take place in order for your number to migrate from SIM to micro-SIM. What’s more, although it’s easy enough to get a standard SIM card for free, you usually have to fork out a few quid to make the jump to micro. If this doesn’t sound like your cup of tea, we’ve created a ‘How To’ guiding you through the steps of cutting down your existing SIM, to micro-SIM size, saving your time and more importantly money in the process.

As you can see it just takes a few simple tools and care and attention and you can knock what would have been a lengthy, arduous process down to just a ten minute instant fix.

What does SIM mean?

The acronym SIM stands for Subscriber Identity Module or Subscriber Identification Module.

What is a SIM card for?

As the full name suggests, the SIM card is a component of mobile phones designed to provide a unique identity for a mobile user or ‘subscriber’ on a specific mobile network. When you use your mobile phone, your SIM card contains your mobile number, various identifiable codes used by your network as well as a small amount of memory, sometimes used to store SMS text messages or contacts. The terms of your Pay Monthly or Pay As You Go plan are linked to your SIM card and not your handset, so can effectively swap phones without affecting your minutes, texts or data allowance provided you use the same SIM card and the handset you switch to isn’t locked to a network.

How many types and sizes of SIM card are there?

Various carriers across the globe offer slightly different chip designs although for the most part they work across devices without issue.

With regards to sizes, there are actually four main types. The normal SIM card, no longer used by modern mobile phones, is about the size of a credit card. The miniSIM is nowadays referred to as a standard SIM and is used by phones such as the Samsung Galaxy S2. The microSIM was initially brought to market by the likes of the Apple iPhone 4 and has seen an increase in popularity by manufacturers since. The nanoSIM is the newly revealed SIM card size, smaller than any consumer SIM card before it and as we mentioned earlier, is only slightly larger than the gold contacts of the chip itself.

What is SIM-only?

SIM-only refers to contracts or tariffs offered by mobile networks that don’t include a phone in the cost. These are recommended if you want to change your contract or network without changing your phone or if you intend on buying a phone separately, but be aware phones sometimes need to be unlocked before they work on a different network. Check out our post on how to get your handset unlocked here and find out more about SIM only plans here.

How do I get a SIM card?

You can order a free SIM card from any of the leading UK networks, online at each of these links. MicroSIMs, or once they arrive nanoSIMs, might cost extra to order.

O2 –
Orange –
Three –
T-Mobile –
Virgin Media –
Vodafone –


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