Holidaymakers are often reluctant to use their mobiles abroad and with good reason as costs can be sky-high. Rules introduced by the European Commission in July 2012 mean using your mobile in Europe has got cheaper but operators can still charge up to 24p a minute.
But BT and Virgin have launched new apps that promises to slash holidaymakers' mobile costs abroad.
Let's take a look at these and other apps that can also be used to cut the cost of your calls home.
BT's new SmartTalk app works by linking the customer's smartphone to their BT home calling plan. Customers can then use the inclusive call allowance on their calling plan on their mobile wherever they are.
There's also the chance to save when calling outside of your inclusive minutes as BT's standard landline rates will then apply, instead of expensive mobile rates.
Another advantage to the app is that some BT calling plans include 0845 and 0870 numbers. So, using SmartTalk, you can call these numbers free from your mobile. And numbers that are free on BT landlines, such as 0800, can now be free when you call them from your mobile phone using SmartTalk.
The app, which is free from the App Store on iPhone or Google Play on Android, works best over wi-fi. In theory it works over any mobile data connection but you'd be at the mercy of data roaming charges if you used 3G.
Virgin Media SmartCall
Rival Virgin Media has designed a similar app to BT SmartTalk with a similar-sounding name: SmartCall.
It launched in November to "select customers" and is expected to be made available to all Virgin Media customers soon.
It will work in a virtually identical way to BT SmartTalk by allowing Virgin landline customers to use the unlimited calls from their home phone talk plan on their smartphone over a wi-fi connection.
If you're on a BlackBerry, you can save on overseas voice calls from your mobile with BlackBerry Messenger.
The latest version, BBM7, allows users to make free voice calls to other BlackBerry users over wi-fi.
BBM Voice allows users to either call a fellow BlackBerry owner directly or instantly switch from text to talk and back again. There's also a split-screen feature so that users can talk and text at the same time.
Skype became a major threat to the landline market a few years ago when it enabled users to make free calls over the internet for free.
Inevitably there are a number of Skype apps available for iPhone and Android which allow smartphone users to make Skype calls from wherever they are.
The apps are best used on wi-fi (if you use 3G you'll be charged for data roaming) and allow users to make video or voice calls over the internet for free if the other person has Skype too. If the person you're calling doesn't have Skype you can make cheaper international calls to landlines or mobiles using Skype Credit.
If you just want to send text messages rather than make voice calls, Whatsapp is a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS.
Already used by pretty much everyone under the age of 25, WhatsApp Messenger is available for iPhone, BlackBerry, Android, Windows Phone and Nokia. It allows users to send text messages over wi-fi rather than the mobile network. This means text messages won't come out of pay monthly customers' text allowance and PAYG customers won't be charged. Travellers can avoid charges for texting to and from abroad.
In addition to basic messaging WhatsApp users can also create groups, allowing you to send each other unlimited images, video and audio media messages.
All the above apps need a wi-fi connection to offer free or cheap calls. If you use the apps on 3G abroad you'll be charged for data roaming – and this can be expensive.
If you're travelling somewhere where you're unlikely to find wi-fi then a PAYG SIM could be the answer.
A local SIM card will offer much cheaper calling rates, both within the country you're in and to the UK, than using your normal tariff.