Success of mobile VOIP application Viber has shown how popular free app-to-app VOIP calling can be, and how wonderful it will be if you get a weekly top-up for 100 minutes free international talktime added to this already awesome offering. New, mobile VOIP service maaii is offering exactly this to give there service the initial popularity push, an attractive 100 minutes free maaiiout minutes talktime every week to make free international calls to non-maaii landline and cellphone users from your iOS and Android devices.

I was eager to review Viber but waited for an Android version to get released, sadly Viber For Android is nowhere to seen - so here we have the review of currently available Viber For iOS.

Viber the free VOIP application for iOS (Android and Blackberry versions expected soon) allows users to call other Viber users anywhere in world for free using their 3G or Wi-Fi connection, the best part of this must-have utility is the sound quality which is simply "exceptional".

Viber uses your phones address book and is always in-sync with it, highlighting contacts that have Viber so you know you can call them for free. To get started all you need to do is, enter your phone number and the confirmation code received via SMS.

We have reviewed several free VOIP service provider from time to time, Voixio is another such free ad-supported VOIP provider, Voixio offers an easy to use flash interface to make free VOIP and video calls worldover, before connecting the call Voixio displays an video advertisement, this is the most promising ad-supported VOIP service we have reviewed.