SIM-only deals are an increasingly popular choice for bill-conscious mobile phone customers navigating the cost-of-living crisis. Based on YouGov data, the SIM-only market is growing between 5- and 15% year-on-year.

While they may appeal for their affordability – you can pay under £5 a month for some 5G data deals – it’s important to watch out for hidden costs while switching, and to make sure your existing handset and the SIM are compatible. Therefore, it may not be as simple as sticking a new SIM in your smartphone.

Below, Uswitch mobiles expert, Rehan Ali lists five key considerations before making the move to SIM-only:

1) Beware any hidden costs in switching providers

On the surface, deciding to move from a fixed £40 monthly contract to a £10 a month rolling SIM-only deal may seem like a great saving. However, it’s important to understand where you are in terms of your fixed contract and whether you have outstanding payments left on your handset, or any early exit fees charged by your provider.

If you’re looking to move to a SIM-only contract, but still have substantial time left within your phone and tariff contract, it’s important to cost up the price of buying your handset outright and whether your provider allows you to leave your contract before the agreed end date.

Often, this can be costly and it’s better to understand when your contract is ending in order to make the move at a time that’s the most cost-effective for you, or see if your provider will let you cancel your contract earlier than planned.

2) Ensure your handset is compatible with your SIM-only contract

The eSIM (an electronic SIM that replaces the need for a physical SIM card) is now being offered by multiple providers in the market, but not all Apple or Android handsets are currently compatible with eSIM technology.

Moving to a SIM-only contract means that your new network is only responsible for selling your tariff, so it’s important to ensure you’re purchasing one that is appropriate for the handset you have.

Consider whether your handset is compatible for an eSIM or whether it’s 5G compatible for a tariff that offers 5G coverage. Specific networks offering 4G-only tariffs can be cheaper, so if you’re using an older handset that isn’t 5G compatible, make sure you choose an option where you’re not paying for something you can’t use.

3) Be prepared with your PAC code

If you want to keep your mobile phone number when you switch, it’s essential to get a PAC code from your current provider in order to port that to your new contract.

The process has become easier over time, with services such as Text to Switch allowing you to request this in order to move.

This service allows customers to get their code quickly, without speaking to pushy sales retention teams or having to wait on hold in order to get the information you need. However, using this service mid-contract can still incur charges that you contractually agreed to, so always check your terms and conditions before trying to switch providers.

4) Is flexibility your priority?

If you’re moving to SIM-only, one of the attractions may be the flexibility in contract lengths. Phone and tariff plans usually tie customers into a contract of anywhere between 12 to 48 months, but SIM-only plans can allow for a rolling monthly contract.

If being able to leave your provider – or move back to a fixed contract is important – then look for a SIM-only deal that is rolling monthly. However, if it’s cost or additional perks that are your priority, a SIM-only contract that is fixed for 12 months may provide you with a cheaper and more beneficial option.

5) Does your new provider offer the same perks?

By moving provider, you’re likely to lose or gain some contract perks that you previously held with your current mobile network. If you currently enjoy free EU roaming as part of your contract, and are moving to a SIM-only deal with a provider that no longer offers this – it could be costly if you’re a frequent traveller.

Think about the perks and benefits you use often in your current mobile contract and try to look at specific SIM-only providers that offer the same. If you enjoy free EU roaming with O2 but are looking to switch, it’s worth looking at providers such as iD Mobile which offers free roaming in 50 countries in the EU, EEA and beyond.

If you have streaming services included in your contract price, there are multiple deals from Vodafone and O2 that still offer entertainment plans as part of a SIM-0nly contract.