Having a smartphone is great for a number of reasons – though most people only consider the immediately obvious benefit of being able to browse on the go, there are some more creative ways to utilize the computational powerhouse you’re holding in your pocket. For example, the Android OS has quite a few apps for it that allow you to talk through VOIP whenever you’re connected to a WiFi hotspot (or if you have good Internet access in general), letting you save quite a lot of money on your monthly contract. Here are the five currently best apps on the market, in our opinion.

#5 Linphone – it’s free and constantly developed, offering a clean and streamlined interface. The program uses the SIP (Session Initiation Protocol) for its connections, giving it a good sound quality and relatively low bandwidth usage (of course, the precise details will depend on the audio codec you’ve chosen to use, but the app handled very well in our tests). The app is also available for desktop computers, with some extra options related to connecting your phone to your computer.

#4 SIPDroid – this app is not only free, it’s open-source too (meaning its source code is publicly available and a large number of people are contributing to it), and also based on the SIP protocol. The app is written in Java (not unusual for an Android app, and it’s still completely functional) which makes it perform slightly slower than most other apps of the same kind – though it certainly doesn’t degrade the overall experience. The app also has a paid version which allows you to transfer calls over different networks, though you won’t need this functionality if you’re a basic user.

#3 CSipSimple – once again based on the SIP technology, this app supports various nifty features such as using your native audio codec, and integrating itself with the filters and rewriting rules of the Android OS. Its functionality is very diverse and you can customize the app to a high degree (you have access to far more options than the average app gives you, including customizing your interface), and all in all this is a great choice for more advanced users.

#2 Skype – it’s Skype! The most popular VoIP app on the PC has its Android counterpart too, and it’s quite well stocked with features. It’s offered in a free or paid version, and features the familiar clean and streamlined interface that made the computer program so popular. If you’re wondering what the paid version gives you, this includes some of the options which are available on the computer client by default – chatting, file transfers and other similar features. Though it’s a bit sad to admit that you can’t use those here, you should remember that you still get the primary function – VoIP – for free.

#1 Vopium – last in the article but number one in our list is Vopium, an app which already got recognition for being the most functional and best-made VoIP app for the Android. It’s completely free, and works by re-routing your calls through a cheap path in order to save ayou as much money as possible. Something the app offers which is lacking in most others, is the ability to retain your SIM card’s telephone number when placing calls, so that you’ll still be recognizable easily – this is certainly a very handy feature to have. Last but not least, it lets you place a call to a non-Vopium device (i.e. a regular phone number), and the app will search for a way to redirect your call and make it cheaper than it would be with the default carrier’s rates.