Global roaming. These two small words can mean a very big headache if you've come home from an overseas trip with a bill as big as your suitcase. Global roaming costs can quickly add up to hundreds – even thousands – of dollars if you use your phone several times a day to make calls and access the net while you're abroad. When travelling overseas, remember these two essential facts:

  • Phone calls and text messages attract a hefty roaming charge.
  • Using the internet comes at a premium.

What will you pay for?

Global roaming calls are charged based on time, but it's also likely you'll be charged a connection fee. You'll pay to receive phone calls and to access your voicemail messages, and the cost of sending SMS and MMS messages while you're overseas is higher too.

Internet access is calculated by the amount of data needed to access email, use apps and visit websites. It's charged by the kilobyte or megabyte, depending on the provider, and be warned, it adds up quickly.

Global roaming alert

Consumers have some help keeping a lid on global roaming costs with a global roaming alert system that all telcos are now required to provide to their customers. Telcos must notify customers who are overseas of the cost of a call, text message and internet access, and provide them with an easy opt-out option. This global roaming standard came into effect in 2013. The government is now also looking into a partnership with New Zealand to limit roaming costs across the Tasman.

Most telcos now offer pre-paid roaming packs for phone and data usage, so customers can manage their costs. Some telcos are more generous than others with data limits and costs.

Turn off roaming on your phone

Adjusting your phone's settings will help you avoid being hit in the hip pocket when you next take your smartphone abroad. Follow these simple steps to help save your travel budget for more important things, like food.

  • Turn off cellular data and 3G to ensure web browsing and other data services are restricted to Wi-Fi internet access only.
  • Turn off data roaming and location services.

iPhone (iOS 7)

Settings > Cellular > Cellular Data, Enable 4G/3G and Data Roaming to OFF.

Settings > Privacy > Location > Services > OFF.

Settings > Notification Centre > turn off notifications for each app.

Android (KitKat)

Settings > Data Usage > Mobile data to OFF.

Settings > Location > turn off location services, GPS and search.

Windows Phone 8

Start > Settings > Mobile network > Data roaming options > Don't roam.

Settings > Location > OFF.

Try a roaming SIM

One option for saving on global roaming costs is to buy a prepaid SIM card to use in place of your usual SIM.

  • Prepaid SIM phone calls and internet are cheaper than roaming rates offered by the Australian telcos.
  • Telstra, Optus and Vodafone also sell prepaid data roaming packs.
  • Shop around for the best deal that suits your needs.

There are a few different companies offering global roaming SIMs, including GlobalSIM, TravelSIM, BackChat Roaming, RoamingSIM, AmaySIM, Woolworths Mobile and GoSIM. We haven't tested these services and so can't recommend one – you'll need to compare prices and find one to suit you.

As a guide, we found one offering data rates starting from 35c per MB, and another offering 39c per min to call an Australian landline from the UK. Be aware though that your phone needs to be unlocked to use one of these SIMs.

Telstra global-roaming data packs start at $29 for 100MB of data. A call from the UK to Australia costs $2 per minute with Telstra. Optus charges $1 per minute for calls, and 50c per MB for data. It also has a $10 per day Travel Data Pack that includes 70MB of data for Asia, Europe and the US.

Vodafone charges $50 for 100MB with a data pack for European destinations. Pay-as-you-go roaming is 1c/KB for plans and 5c/KB for prepaid. It also has a $5 per day add-on for Red plans, which lets you use phone and data from your plan in the US, UK, Asia and Europe.

Unlocking your phone

Smartphones bought through a telco service provider such as Telstra or Optus are almost always locked to their network, which means the phone can only be used on through their service. While this isn't an issue for use with that carrier in Australia, it can be problematic if you want to use an alternative SIM card when travelling overseas to get cheaper rates for phone calls and internet access.

To unlock your phone, you need to ring your service provider and request a code. However, you'll be charged a fee that can range from $50 to $150 depending on the device and whether it's on a plan or owned outright.

Tips to avoid global roaming bill shock

  • Switch off. Don't make calls, send text messages or access the internet from your mobile unless it's an emergency.
  • Turn off voicemail for the duration, so you don't end up paying for phone messages.
  • Turn off data roaming using your phone's settings.
  • Use travel/flight mode on your phone.
  • Turn off all updates, notifications and location services, such as mapping, for the duration of your travels.
  • Check with your telco about the costs of calls from the countries you're visiting before you leave.
  • Buy a global-roaming data pack. Your phone provider should sell these for both prepaid and post-paid plans.
  • Set usage alerts so you don't go over your limit.
  • Use an online calculator to work out the amount of data needed for internet-enabled services you're likely to use.
  • Research the locations before you leave home so you can plan to make internet (VoIP) phone calls or send emails each day when it's convenient.
  • Use Skype or a similar internet-based phone service via Wi-Fi to make free or very cheap phone calls.
  • Use free internet in Wi-Fi hot spots in cafés, hotels, airports or shopping centres as often as possible.
  • If you have to send documents or attachments while you're away, limit them to times when you're using free internet.
  • Buy a prepaid global-roaming SIM card. You can buy one in Australia before you leave, or in the country (or countries) where you're travelling. These can be used in unlocked phones.