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SIM-only explained: A guide to BYO phone plans

Overwhelmed by SIM-only options? Here's everything you need to know to before you buckle down and pick out the best BYO mobile and phone plan.

Fergus Halliday
Jul 17, 2023
bullet5 min read

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With so many providers and acronyms in the mix, it’s hard to know where to start when it comes to SIM-only or BYO phone plans. To help clear up any confusion, we’ve put together a guide that covers everything you need to know about SIM-only phone plans before you sign up for one. What they are, why you might want one and how they rate against the alternatives when it comes to things like pricing, perks and more. 

Before we dive into the details, here’s a quick snapshot of the most popular SIM-only plans in our database with at least 20GB of monthly data.

What is a SIM-only or BYO phone plan?

Everything you need to know about SIM-only phone plans

The phrase SIM-only and BYO phone plans can be quite confusing due to the many acronyms involved, but in simple terms, it means that these plans do not include a device and you will need to provide your own.

The advantage of this is that you won't have to pay extra for a device, making it a great option for those who want to minimize their monthly expenses or keep using their current device for as long as possible.

SIM-only plans can be either contracted or non-contracted, but contracted plans usually have shorter durations compared to phone plans. Typically, the contract period for SIM-only plans is no more than 12 months, while phone plans can last for 24 or 36 months.

Which providers offer SIM-only plans?

Most Australian mobile providers deal in SIM-only plans. The list here includes the big three - Telstra, Optus and Vodafone - as well as the Mobile Virtual Network Operators (MVNOS) who sell their services atop the same networks. Safe to say, Australian consumers have plenty of options to choose from when it comes to finding a SIM-only provider or plan that meets their needs.

What is the difference between a prepaid plan and a SIM-only plan?

If you want to get technical, both prepaid and postpaid phone plans are SIM-only plans. After all, all you’re really paying for is the little card (or eSIM) that gives you access to the network used by your chosen provider.

That said, it's far more common for the term 'SIM-only' to refer to postpaid mobile plans specifically. The main difference between this type of phone plan and a prepaid one has to do with how and when you pay your mobile bill.

For prepaid phone plans, you pay upfront. The terms between you and your provider decide how much talk, text and data you get, as well as how long you have to use those inclusions are locked in ahead of time. For that reason, the ability to know exactly what you’re getting and how much you’re paying for it makes prepaid plans a great option for those who like to keep to their budgets.

If you run out of prepaid data, you’ll have to either pay for more or wait until your next recharge. SIM-only and BYO device plans work in the opposite way. You pay for your talk, text and data at the end of your billing cycle rather than at the start of it.

As opposed to prepaid plans, if you go over your data allowance with this kind of plan, you’ll be charged for excess data (usually at a higher rate) rather than having your use cut off. There’s peace of mind in knowing that you’ll stay connected no matter how much data you use, but that security can come with a surcharge.

Why should I choose a SIM-only plan?

SIM-only plans aren’t going to be for everyone, but they are going to be a good fit for consumers who:

  • Already own their own device 
  • Don’t want to upgrade to a new phone
  • Can’t afford to buy a new phone outright 
  • Are looking for a good value plan to tide you over until you can afford to upgrade
  • Want to pay less on their monthly phone bill
  • Don't want to be locked into a long-term contract

Are SIM-only plans cheaper?

SIM-only plans can often end up cheaper than the alternatives, but it sometimes depends on what you're comparing them to. For instance, SIM-only plans usually come out ahead of traditional phone plans as you aren’t paying any handset fees on top of your service.

Generally speaking, the wide range of providers also means more competition and lower prices. If you’re willing to look beyond the big three providers, there’s a lot of savings to be had. 

Depending on the plan and provider, opting for a SIM-only plan and buying the new iPhone outright could save you a sizable sum compared to getting the device on a contract phone plan through Telstra, Optus or Vodafone.

Here’s a quick snapshot of the cheapest SIM-only plans in our database with at least 20GB of monthly data.

What are the best SIM-only plans?

SIM-only plans aren’t one-size-fits-all, so the best one for you is going to depend on what your individual needs are. It’s easy to crunch the numbers and calculate which one offers the best ratio of dollars-to-gigabytes on a given day, but that figure doesn’t account for the value of things like the perks and coverage that a given provider might be able to offer. For example, the value of Telstra’s superior regional coverage is going to matter a lot more if you aren’t living in a metropolitan suburb.

If you’re unsure where to start, we have a number of guides to help you find the best heavy-use and everyday-use SIM-only plans and work out how smaller providers rate against the SIM-only plans available through Telstra, Optus and Vodafone. 

Here’s a quick snapshot of the SIM-only plans in our database with at the most monthly data.

Can I keep my number if I switch to SIM-only?

Regardless of whether you opt for a SIM-only plan or a prepaid one, you should be able to take your current phone number along with you. Having to inform all your friends and family to update their contact details for you is always a hassle, but it’s easy enough to avoid. 

It might take a few extra steps, but the long-term benefits of keeping your phone number are usually worth it. 

How do I switch to a new SIM plan?

Swapping from your current mobile provider to a new one might sound complicated and time-consuming, but it’s usually an easier process than you might expect. These days, signing up for a new plan can take less than 10 minutes. The systems that move your phone number from one provider to another (a process known as porting) can sometimes make the necessary changes in less than half that time.

In order to switch to a new SIM plan, you’ll need the following:

  • A phone or computer
  • A current phone plan
  • A driver’s license (or another form of identification)

If you're buying a new phone plan online the process, there are a few steps to this process. 

  1. Decide on your new SIM-only plan
  2. Place your order via the provider’s website. If you’re ordering a postpaid phone plan, your provider may need to run a quick credit check and request additional details from you. 
  3. Wait for your provider to send you a new SIM card in the mail or activate your plan via eSIM. If you’re opting for the former, this may take a couple of days. 
  4. Once your SIM card has arrived, you’ll need to activate it. This is usually done through the website or app of your chosen provider. 
  5. After you have activated your new SIM, the process of porting your phone number from your old provider to your new one will begin. This won’t require anything but time from you. In most cases, this won’t take more than a few minutes. However, in some cases, It can take up to a few hours. 
  6. That’s it! Enjoy your new phone plan.
Fergus Halliday
Written by
Fergus Halliday
Fergus Halliday is a journalist and editor for Reviews.org. He’s written about technology, telecommunications, gaming and more for over a decade. He got his start writing in high school and began his full-time career as the Editor of PC World Australia. Fergus has made the MCV 30 Under 30 list, been a finalist for seven categories at the IT Journalism Awards and won Most Controversial Writer at the 2022 Consensus Awards. He has been published in Gizmodo, Kotaku, GamesHub, Press Start, Screen Rant, Superjump, Nestegg and more.

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