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A SIM-only plan gives you a mobile service without a phone: you bring a phone you already own and put in the new provider's SIM or eSIM. Because you are not paying off a handset, you can usually leave at any time on a month-to-month or prepaid plan, which is why SIM-only is the cheapest and most flexible way to buy a mobile service in Australia.
The trade-off is that nobody checks your phone for you. Before you switch, make sure the phone is unlocked, supports the new network's 4G bands and Voice over LTE, and handles eSIM if you want one. Then compare plans on the network, data allowance, speed cap and what happens when you run out, using each plan's Critical Information Summary.
By Better Rate Mate Editorial Team ยท Last reviewed
SIM-only comes in both forms. A prepaid SIM-only plan is paid in advance for a recharge period, commonly 28 or 30 days, or a long-expiry period such as 365 days. A postpaid SIM-only plan is billed monthly, most often month-to-month, though some providers offer a lower price or bonus data for a 12-month term with an early termination charge.
Moneysmart notes that some SIM-only plans require a minimum 12-month contract. The minimum term and the maximum early termination charge are both in the top section of the Critical Information Summary, so you can see the commitment before you sign. Our prepaid vs postpaid guide covers the differences in detail.
Check three things before you move your number:
The plan with the best coverage for you is one on the network that works best where you live, work and travel. The brand does not change the towers: an amaysim plan uses Optus's towers, a felix plan uses Vodafone's, and an ALDI plan uses Telstra's wholesale footprint.
Telstra's full network covers the largest area, but most Telstra resellers use the smaller Telstra Wholesale network, so a cheaper Telstra-network plan is not automatically Telstra coverage. In regional areas Optus and Vodafone now share towers. The fairest comparison is the operators' standardised coverage maps, which the ACMA has required since 30 June 2026. Our network pages list every brand on Telstra, Optus and Vodafone.
Price and data are the headline, but these are the features that separate two plans with similar headlines:
| Feature | What to look for |
|---|---|
| Network and tier | Which operator's network, and for Telstra resellers whether it is the full network or Telstra Wholesale |
| Data allowance | Enough for your real use; check your phone's usage screen for the last few months |
| Speed cap | Many plans cap speeds at 100, 150 or 250 Mbps; matters most for hotspotting |
| 5G | Included on the plan, not just offered by the brand |
| When data runs out | Excess charges, automatic top-ups, or slowed speed with no extra charge |
| Data rollover or banking | Whether unused data carries over and how long it lasts |
| Recharge or billing period | 28-day plans mean 13 payments a year |
| International calls and roaming | Included countries and minutes, roaming packs and pay-as-you-go roaming rates |
| eSIM and Wi-Fi Calling | Supported on your phone and on the plan |
| Minimum term and exit costs | Month-to-month or fixed term; the maximum early termination charge |
The Telecommunications Consumer Protections Code requires providers to send free alerts when you reach 50%, 85% and 100% of your included data or value, no later than 48 hours after you pass each threshold. The alert is your cue to check what the plan does next.
Plans handle running out in one of three ways: they charge for extra data, they add automatic top-ups, or they slow your speed without charging. If you are often over your allowance, a larger plan is usually cheaper than paying for top-ups; if you rarely use half, a smaller plan is. Cancelling automatic top-ups on a plan that has them is worth doing if you want a hard spending limit.
A phone on a plan spreads the handset cost over 12, 24 or 36 months. The ACCC warns that where the handset is on a longer term than a month-to-month service, you will have to pay off the balance before leaving the provider, and Moneysmart points out you do not own the phone until it is paid off. Missing repayments can affect your credit report.
Buying a phone outright, or keeping your current one, and taking a SIM-only plan leaves you free to change plans whenever a better one comes along. It is usually the cheaper path over two years if you can afford the handset, but compare the total: the device repayments plus plan fees against the phone's outright price plus a SIM-only plan at the same data.
Sign up with the new provider and ask to keep your number. The new provider starts the port, and before it goes ahead it must confirm you control the number, usually with a one-time code sent to your phone. Keep your old service active until the port completes; the ACMA says a mobile port usually takes about three hours. Then put in the new SIM or install the eSIM. Switching and keeping your number has the full process.
A mobile plan without a phone. You use a phone you already own with the provider's SIM card or eSIM. SIM-only plans can be prepaid or postpaid.
One on the network with the best coverage where you are. Telstra's full network covers the largest area, but most Telstra resellers use the smaller Telstra Wholesale network. Check the standardised coverage maps for your addresses before choosing.
Most postpaid SIM-only plans are month-to-month, but some have a 12-month term with an early termination charge. The minimum term is in the top section of the Critical Information Summary.
It changes every few weeks as providers reprice and run introductory offers, and the cheapest plan depends on how much data you need. Compare the yearly cost at your data level, counting 13 payments for 28-day plans and the price after any discount ends.
Yes. Your new provider ports the number; your old provider must release it even if you owe it money, although you still have to pay what you owe.
No, as long as your phone is unlocked and supports 4G Voice over LTE. Text 3 to 3498 to check whether a phone will work now that 3G has closed.
