If you're going overseas with an iPhone, here are the top five things you must know before you go.
#1 Don't use data roaming
The iPhone uses a lot of data, which can result in incredibly expensive global roaming bills. Global roaming rates are $10 - $20 per MB depending on your telco (Optus being the most expensive, Vodafone being the least).
Even moderate usage of an iPhone could easily result in usage of 100MB in a week or two, and that would result in a global roaming bill of $1000 - $2000!
A much cheaper option is to buy a prepaid SIM card with data enabled at your destination. Not only will you get internet access at affordable rates (literally 99% cheaper than global roaming), you'll be able to make phone calls without worrying about being charged dollars per minute, too.
We've previously published guides on the best SIM cards for various countries:
USA - T-Mobile or AT&T or Tru
UK - Tru
Europe - MaxRoam or Droam
Hong Kong - Three
Singapore - Bridge AsiaRoam Data SIM
Malaysia - Bridge AsiaRoam Data SIM
Indonesia - Bridge AsiaRoam Data SIM
The Philippines - Bridge AsiaRoam Data SIM
Thailand - Bridge AsiaRoam Data SIM
India - Bridge AsiaRoam Data SIM
Sorry if the country you're travelling to isn't on the list yet -- we're still researching the best options for prepaid SIM cards in different countries.
#2 How to ensure your iPhone is unlocked
In order to use a foreign SIM card, you'll need to ring your telco and make sure your iPhone is unlocked.
Telstra, Optus and Vodafone all provide free unlocking for iPhone customers, even if you're still within your initial contract period.
Optus: 1300 300 937 or 02 8082 5678
Telstra: 1800 474 663 or 02 9242 0213
Three: 133 320 or 02 9034 8081
Virgin Mobile: 13 63 69 or 02 8860 9848
Vodafone: 1300 650 410 or 0414 141 414
Don't leave it to the last minute, though -- it can take five to 48 hours for the unlock to go through.
There is another catch: even if your telco unlocks your iPhone at their end, it will only actually be unlocked if you insert a different SIM card into it, and then sync it with iTunes.
This means, unless you are travelling overseas with a laptop that is normally synced with the phone, you have to get a different SIM card while you are still in Australia, put it into the iPhone, and sync it with your computer in order to complete the unlock.
The easiest way to achieve this before going overseas is simply to borrow a SIM card from a friend who has the same model of iPhone but on a different network, put it in your iPhone, and then sync it with your computer. iTunes will give you a message saying that the phone has been successfully unlocked.
If you don't have a friend with an iPhone on a different network, you can buy a prepaid SIM card at a service station or supermarket and put it in your iPhone. The $2 Amaysim SIM card is a good one to buy, as it will fit in any model of iPhone, including iPhone 4, and is on sale at 4,500 locations around Australia.
#3 Bring a SIM card cutter with you
For reasons known only to Apple, the iPhone 4 uses a different size SIM card to every other phone in the world -- a "Micro SIM".
Although telcos that sell iPhones all offer Micro SIMs, they may not be readily available for prepaid customers who walk in off the street -- as you will be doing.
Fortunately, the electronics of a Micro SIM are exactly the same as a normal-sized SIM, so you can easily cut down a normal-sized SIM to Micro size. The easiest way to do this is with a SIM cutter, which works exactly like a holepunch.
You can buy them on eBay very cheaply -- at the time of writing they were available for $1 each, with $4 postage to Australia (from Hong Kong).
To use the SIM cutter, you simply slide the normal size SIM card into the cutter's slot, squeeze the handle down, and an iPhone sized Micro SIM will pop out the other side.
(Bonus tip: if you've never actually had to change the SIM card in your iPhone before, you'll discover it's a bit different to other phones in terms of where the SIM card slot is. Look for the pinhole on the top or right edge of the phone, which you'll need to stick a paperclip into to pop out the SIM tray.)
#4 Be prepared to fiddle with the APN setting
When you buy an iPhone from an Australian telco, it comes with all the right settings for it to connect to the internet.
However, when you swap the SIM card over to a foreign one, you'll need to manually change the "APN" setting, which is a setting that allows the phone to connect to the internet with the new telco.
When you buy a prepaid SIM card, make sure you check the instructions that come with it (or ask at the shop, if it's a telco shop) to find out what the correct APN is.
You may be able to change the APN on your iPhone just by going to:
Settings > General > Network > Cellular Data Network
Then look for the "cellular data" heading, which should be at the top of the page, and change the details in the APN field, and if specified by the telco, the username and password as well.
If you can't access that settings screen, you'll need to change the APN a different way -- there's a website that can do the work for you, called Unlockit.co.nz. You will need to be connected to a Wi-Fi hotspot (often found in hotel lobbies, or Starbucks/McDonalds) in order to access the website through the iPhone's browser.
Go to Unlockit.co.nz, and follow these instructions.
In this example, we've used AU - Truphone as the network (as if you were using a Tru SIM card) but generally, in step C, you'll need to select the country name and telco that you bought the SIM card from.
#5 Don't expect "personal hotspot" to work
Unfortunately, the iPhone's "personal hotspot" feature that lets you turn the phone's internet connection into a Wi-Fi hotspot for use with other devices like a laptop or iPad, is unlikely to work with a prepaid SIM card, as it requires approval from both the telco and Apple.