Even the seasoned travellers have nightmares about returning from holidays to face a $2,000 mobile phone bill.
But if you're planning a trip abroad, there's plenty you can do to minimise roaming charges. Whether it's knowing what to set up before you leave or what to do when you're on the ground, here are our tips (some of them very quick and easy) to prevent bill shock.
Before you leave
Record a new voicemail
When you're travelling you often want to triage important calls. Before you fly out, record a new voicemail message to tell people the dates you're away, and ask them not to leave a message unless it's an emergency. Alternatively, leave your email address so people can still contact you, but you can choose when to respond. Don't be the person standing in LAX listening to voicemails from your hairdresser (yes, that was me).
Set up call forwarding
If your partner is staying home with the kids or if your boss is happy to field work calls while you're away, set up call forwarding. By entering a few keystrokes while you're still in Australia on your local network, you can choose to divert some or all calls, and send them to another number or straight to Voicemail. Telstra, Optus, Vodafone and Virgin Mobile all offer this service.
Set up pre-paid roaming
Vodafone is a standout on global roaming, with 50 countries included in its $5 Roaming add-on. Once activated, you get all your postpaid data, text and call inclusions like you normally would at home for AU$5 a day (or $0 in New Zealand). If you don't use your phone on a particular day of your holiday, you also don't pay for that day.
Telstra customers can pay in advance for an International Travel Pass to get overseas calls and data. Telstra has simplified pricing, moving away from reasonably costly monthly passes to pay-by-the-day passes. At AU$10 a day for most countries except New Zealand (which is AU$5 a day), it's still double the price of Vodafone and the 100MB daily data limit doesn't roll over day-to-day, but you will get unlimited calls and texts.
Optus post-paid customers can pre-purchase an Optus Travel Pack for AU$10 a day to get unlimited talk and text plus 50MB of data. You can stack these packs up, so AU$50 will get you 250MB to use any time over 5 days, and coverage includes plenty of popular destinations across Asia, Oceania, North America and Europe.
Buy a travel SIM (in Australia)
If you're leaving from Sydney or Melbourne international airport, buy your SIM before you leave through SIMCorner -- you pay in Aussie dollars and then activate when you land, and the rates are good.
Globalgig's Traveller+ Plan gets you 1GB for AU$30 per month in Zone 1 countries (most of Europe, UK and US). Zone 2 countries (including Asia, South America and the Middle East) will cost you AU$0.25 per MB, but that rates well compared with AU$0.25 per MB everywhere for Australia Post's Prepaid Travel SIM or a whopping AU$1 to $3 per MB for pay-as-you-go roaming with the major carriers.
Download offline apps
Just when you need Google Maps the most, you don't want the data bill that goes with them. Instead, you can download Google Maps to use offline. Microsoft's Here Maps will also let you download maps to use offline, but you'll need a Microsoft login (you can use your Xbox or Hotmail login). There are also a range of offline map apps on the Google or Apple app store, though it's worth paying for better quality. If you're standing in freezing New York desperately trying to find the closest Shake Shack, there's a lot to be said for a map that doesn't load the CBD on to your screen block-by-block.
While you're at it, consider translation apps that work offline -- Google Translate has downloadable language packs to help you find the nearest bathroom when you're data-free.
Switch off data
When the flight attendant asks you for the fourth time to switch off your phone, be sure to turn off mobile data in your settings before you do. Another great way to avoid any cellular activity when you land is to keep your phone in Airplane Mode. That way, you won't be hit with data roaming charges for apps that are working in the background when you land (here's looking at you, Facebook).
When you're overseas
Don't answer the phone
It may seem obvious, but there are plenty of people who forget that roaming charges apply for receiving calls overseas, as well as making them. Go into true holiday mode and ignore incoming calls (callers will get your voicemail telling them you're overseas anyway).
Embrace your inner teenager and spend your time texting rather than calling. You'll still pay a mark-up, but it's a good way to get important messages through to travel buddies when you're planning where to meet for dinner.
If you want to avoid SMS altogether, remember there are plenty of messaging apps that work over the internet, rather than traditional phone networks. These "over-the-top" apps, such as iMessage, Facebook Messenger, WeChat, WhatsApp and even Snapchat, still use data but they're great when you're on free Wi-Fi .
Often the go-to when you're at home trying to video chat with friends overseas, Skype is also great for calling home when you travel. You can use regular Skype-to-Skype calling, but with the purchase of Skype credit you can also ring standard mobile and landline numbers anywhere in the world for a fraction of the usual cost, all while using a free Wi-Fi network or hotel Wi-Fi.
Find free Wi-Fi
Free public Wi-Fi networks are ubiquitous in Europe and easy to find in coffee shops, and if all else fails, remember the holy trinity of free Wi-Fi: Starbucks, McDonalds and Apple Stores. But remember, you're on an open network, so check out our tips on how to stay secure on public Wi-Fi, and avoid things like internet banking.
If you're with Telstra for home broadband, sign up to the Telstra Air network to get access to a network of hotspots overseas and your data usage will come out of your home broadband allowance.
Be on the lookout for internet access when choosing your hotel, but watch out for wording. "Free internet" might require you to bring a physical Ethernet cable and "Free Wi-Fi in hotel" could mean that there are hotspots in common areas, but not in individual rooms.
Some hotels will still gouge you on per-day Wi-Fi charges, and some even charge per device, but you can get around this by tethering laptops and iPads to your phone data connection, or by buying your own hotspot.
Finally, bear in mind that hotel Wi-Fi isn't always renowned for its speed, and remember this isn't your home network, so stay secure.
Cheating on your telco
Buy a SIM when you land
A great option in big Asian cities like Singapore and Taipei, you can often pick up a tourist SIM that offers crazy data allowances for a short period at a low price. In other places with less established telco networks (for example, Vietnam) your telco might not even offer discounted roaming, so it's cheaper to get a SIM on the ground.
You can often find travel SIMs at the airport, and most countries require you to show your passport when you buy your SIM, so it's worth buying when you land (even if you just want to get to your hotel!).
But do your research before you leave. What are the best telcos in the country you're visiting? Is there an AT&T or Vodafone store near your hotel? Talk to friends who have travelled before you (they may even have a SIM floating around from their last trip) and if all else fails, ask at the hotel front desk.
Importantly, if you take this route, you need to ensure your phone isn't locked to your home network before you leave.
Get a dual SIM phone
If you get a cheap data deal with a travel SIM but still want to get calls to your own number, a dual SIM phone is the way to go. Often priced at the entry level in terms of handsets, you can set up your overseas-bought SIM to handle data and your home SIM to handle calls and texts. The Chinese manufacturers specialise in these phones, so look for brands like Oppo and Huawei.
A great option for regular tourists or business travellers, the dual SIM phone also means you're not losing your brand new gold iPhone if your handset gets lost, stolen or damaged abroad.
Which brings us to our last tip: No matter what you do with your mobile before you go, be sure to back up before you leave (and, if possible, while you're on the road) in case you lose your phone. And even if you're a free spirit back home, put a PIN or swipe lock on your phone while you travel, just in case.
Update, 12 July, 2017: Added detail about Telstra's revised Travel Pass pricing.