You can download the app for free from the iOS App Store or from Google Play.

iPlum lets you finally turn your iPad or iPod Touch into a phone! Of course, it also works perfectly with iPhones and Android phones and tablets.

iPlum is at heart a VoIP app which lets you make calls and send messages via your data connection, which are then converted to the mobile or landline network by iPlum's servers.

For $1/month iPlum gives you a real U.S. phone number which can also receive calls and with a true caller ID. The number is unique to you. This is not essential; you can use iPlum for free without a phone number, and still call and text other iPlum users, as well as make free unlimited U.S. toll-free calls.

If you are a visitor to the U.S. this gives you a local number to use without having to set up any SIM cards, provided you have data available through WiFi or your carrier. The call costs are vastly lower than international roaming. Your contacts can reach you easily on your iPlum number.

Like Skype, iPlum to iPlum calls are uncharged. Calls and messages to the mobile or landline network are as low as 1c per minute. Unlike Skype, iPlum gives you voicemail for your smartphone and tablet.

iPlum can also offer you privacy by handing out your iPlum number instead of your real personal mobile number.

Call credits can be purchased in multiples of $5, $10 and $20 via in-app purchases.

It is free to set up and try out iPlum so there are no risks in trying it out. Although iPlum is competing against the likes of Skype and Lync and WhatsApp it offers compelling features such as voicemail, free unlimited U.S. toll-free calls, and a dedicated U.S. number no matter where you are.