At the very minimum you will be paying for the data transmitted (via your 3G or WiFi/broadband accounts) But this is minimal. Get yourself a SIP account with a local provider. I use VoipVoip who are in the UK and charge from .02 to .06 cents per min depending on where you call. Once you create an account the 'call using SIP' option is available in the dialler. Skype is integrated into the N900, you need only to add your account details. Viber calls are free of charge (excepting data) to others that have the app loaded but I haven't yet found that solution on Meamo. Hope this helps.