For those new to Apple and iOS, iMessage is the new messenger service for iOS devices that was launched with iOS 5, allowing you to send messages for ‘free’ between iOS devices. Instead of using SMS/MMS it uses data traffic from your data allowance to send the message, which is why if you are abroad it can end up costing you more than you expected.
We all know that data roaming abroad quickly can rack up some serious spending as depending on the country you travel to, data traffic over mobile networks can be expensive, and much more so than for example sending an MMS picture message. The thing with iMessage is that is becomes the default option for sending messages between iOS devices unless you turn it off, so if you don’t disable data roaming when abroad and you send messages to a fellow iPhone owner you can end up paying more than you have to.
For example, i’m an O2 customer here in the UK, and if i was travelling in the US a picture message at 200kb would cost me about 26p to send through MMS. However if i was sending it using iMessage the same 200kb picture message would end up costing me approximately £1.20 (based on O2′s stated £6 per MB price for data traffic from the US). That is a big difference in cost, so be careful how you send messages when abroad. The cheapest option is always to find a free wi-fi that you can connect to, but if that is not available, you might want to turn off iMessage while abroad and use the standard SMS/MMS option instead.
Check with your own network before traveling how much SMS/MMS messages cost compared to price on data traffic from the country you are traveling to.
To switch of iMessage go to ‘Settings’ –> ‘Messages’ where you will find the on/off button for iMessage.