iPlum lets you call internationally for as low as one cent per minute

Traveling internationally is pricey enough as it is, but international roaming can send the cost soaring even higher — T-Mobile’s calling rates, for example, range from $1.99 (Aruba) up to $10.79 (Diego Garcia) per minute. That’s where iPlum comes in: by leveraging your phone’s Internet connection, the service is able to offering dramatically lower rates than many of its competitors — as cheap as one cent per minute.

It works like this: You install the iPlum app on your smartphone or tablet, then sign up for an international calling pass. For $1 a month, you can place encrypted calls over a Wi-Fi or cellular connection from anywhere in the world at low per-minute rates, and calls to other iPlum users for free. You get a real U.S. phone number that others can use to reach you, plus a bevy of extras including unlimited toll-free calling to the U.S., the ability to send and receive text messages, and a second, “virtual” phone number for privacy.

iPlum’s conceit — cheap voice-over-Internet — isn’t original. Apps like Whatsapp and Viber operate in much the same way, running atop a data connection to carry voice to and from your handset. But those services require that all calling parties download an app, a difficult proposition for landline users. Some VoIP alternatives such as Vonage and Skype offer international landline calling, but usually at inflated rates; a pay-as-you go Skype call to a landline Germany, for example, costs 2.3 cents per minute.

iPlum has its downsides. Its reliance on an Internet connection puts it at a competitive disadvantage to companies like Rebtel and Ringo, which offer cheap international calls over local cellular connections. But compared to major U.S. carriers, iPlum’s pricing ain’t bad: an entry-level international calling add-on costs $10 per month on T-Mobile and $30 on AT&T.

iPlum is compatible with Android and iOS, and is available from the Google Play and App Store.