For the past year or so, Vonage has been adding to its international VoIP game, and the latest new feature is roaming. That's right, the company's iOS and Android apps will soon have Vonage Mobile Roaming, meaning folks can take all their incoming calls over WiFi wherever they go without fear of ringing up a ridiculous cellphone bill. The catch? The service is in its trial phase and you've gotta reside in the UK, Netherlands, Spain or Italy to take advantage of this frugal feature. Those interested (and eligible) can sign up to get in on the action at the source below.