What is Sim Free?

Andy Simpson

There’s been a lot of confusion over the years about the terms “SIM free” and “unlocked.” They’re phrases that we all hear, and they’re often used interchangeably, but what do they actually mean?

What is a SIM card?

First, we need to know what a SIM card is. A SIM card is a small piece of plastic and circuitry that sits inside your phone, uniquely identifying it to a specific network. For example, you might have an EE sim card, which allows you to connect to EE’s network and provides you with a unique phone number so that you can make calls, send texts and connect to the internet.

SIM cards are removable, so you can bring your phone number and mobile service with you when you switch from one phone to another. You can also get new SIM cards when you sign up for a new pay-as-you-go or monthly contract, letting you switch networks while keeping the same phone.

What locked and unlocked really mean

A phone is said to be locked if it can only be used with one mobile network (or group of mobile networks). For example, most phones sold by O2 on a monthly contract or pay-as-you-go will only work with O2 SIM cards.

Conversely, an unlocked phone can be used without restriction on multiple mobile networks, just by switching the SIM card in the phone for a different one. These phones might have had their network locks removed after purchase, or they might not have existed in the first place.

What SIM free really means

A phone is sold SIM free if it does not come with a SIM card. Instead, it’s up to you to provide and install a SIM card for the phone. A SIM free phone can come locked or unlocked. If it is unlocked, then any SIM card that physically fits will work. If it is locked, then you must insert a matching SIM or unlock the phone.

All phones sold on Mobile Fun are both SIM free and unlocked, meaning they come without a SIM card, and will work on all networks.

Why are SIM free phones more expensive?

SIM free phones have a higher price up front than phones sold on contract, with flagship phones costing £500 or more. In contrast, the same phone might cost nothing up front on a monthly contract. This is because your network is spreading the cost of the phone across your monthly bill for the length of your contract. This reduces your up-front expenses, but often raises the price in the long run.
Shop Sim Free Phones >

Why choose SIM free?

  • Upgrade your phone whenever you want and get a higher resale value
  • Shop for a phone and a contract separately to get the best deal
  • Choose to use Pay As You Go or find your own best contract
  • No network apps, branding or locked features
  • Perfect for travelling abroad

Questions? Comments?

I hope I’ve answered your questions. If anything isn’t clear or you’d like us to cover something else, please let us know by writing in the comments below or speaking to us on Twitter @mobilefun.

30 thoughts on “What is Sim Free?”

  1. Yeah, that should work — but check by calling Sprint and asking them if it’ll work. I’m not based in the USA, so I can’t say for sure — you might find you miss out on a few features.

  2. Just Wondering, If I Were To Have A iPhone 6s with sprint, and I were to buy a sim-free iPhone 7 plus would I be able to insert my sprint sim into the new sim-free iPhone 7 plus?

  3. I’m new to MobileFun and this is a really thorough guide for someone looking to build their knowledge. I wondered if you’ve done a review of O2 Star Trader/giffgaff? I’m not entirely sure how giffgaff works but I know with Star Trader you get £5 for each sim card that you can get someone to activate. I’m just starting on it and articles like this are a big help so that I can properly discuss with customers. Great!

  5. Hi there, If I buy a HTC m8 on a contract from vodafone (UK) would my Portuguese vodafone sim card work on this same phone when used in portugal ?

  6. My father is 86 and just needs a phone for calls and text He does not have internet. He tied himself into a contract which was not a good deal but it is coming to the end so I am looking for the cheapest deal for him. Could he just use his existing phone with a new basic contract or should he look for one with new phone It is so confusing with cash backs etc. He changed from Pay as you go to a contract because he did not want to keep topping up. He does not use it much, mostly when not at home for emergencies or when is in hospital etc. Are there any special deals for senior citizens with phone that are easier to use.

  7. It depends on which frequencies/bands your phone supports. Look up the phone you have on GSMArena, then check that against the bands that Airtel/Vodafone provide.

  8. I’ve got a UK Sim free phone, bought in the UK. I’m moving to India next month and I’m wondering whether I can use Airtel/Vodafone sim in India with my phone. Some people say I can’t use this phone in India for 3G and some say it won’t work at all. Why can’t I use a ‘sim free’ phone in India? Might be due to different bands/frequencies?? Please clarify.

  11. Can I buy a UK sim free phone and use Indian Sim card. The reason why I’m asking is I’m a visitor the UK and I’m looking to buy a phone here. Once I go back to India, I want to know if I can use the network sim cards in India with the sim free phone I purchased in the UK?

  15. i want to buy a sony xperia tipo but its a sim free phone as they dont sell it on my network 3, will my 3 contract sim card work in this sim free phone, i checked the specifications on this phone and the phone runs 3G and it is listed as 2100/UMTS ?, i dont want to buy the phone and then the sim card dont work i spoke to my network provider they sed it wudnt be a problem but im not certain can anyone help? or has any 1 come accross the same sort of problem?

  16. Take it back to the store :) If it’s meant to be unlocked, then it should work. If it isn’t unlocked, you’ve been misled by the woman you spoke to.

  17. bought an Alcatel 3g phone from Tesco as the woman said it would work with 3.. got home and it says emergency calls only.. can anyone help?

  18. hello! just wanna ask if “simfree” phones can have GSM-network sim inserted? Thank you.

  19. Am new to MobileFun & found explanations really helpful. However, also newbie to smartphones and would appreciate suggestion as best to buy; want it to be sim-free as do not want to be tied to any network. Hope you can help because everything changes to quickly that I feel somewhat overwhelmed by technology – hard to keep on top of things.

  21. Great article, thanks. I am traveling to the Uk in May and would liken to buy a ‘Pay as you Go’ phone. Where do you get Sim cards and at what cost. Will be there 3 weeks and expect minimal use of the phone, guessing 40-50 calls max.
    Also have a iPAD, can I get a month 3G contract to use there?

  23. you can get a phone that you can put two sim cards in or 3 sim cards in look on ebey and there are lots on there i got a phone where i put 3 sim cards in

  26. I have two pay as you go phones. One I use in Spain (Vodafone Espana) and one I use in the UK (Vodafone UK). Both, obviously with different numbers. My question is. Can I buy one good smart phone, put both cards in it and switch from one to the other whichever country I’m in?

  27. I have two pay as you go phones. One I use in Spain (Vodafone Espana) and one I use in the UK (Vodafone UK). Both, obviously with different numbers. My question is. Can I buy one good smart phone, put both cards in it and switch from one to the other whichever country I’m in?

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