Like Skype, Barablu lets users make PC-to-PC calls, but they take it a step further by also offering mobile to mobile calls. Using a compatible GSM phone with Wi-Fi enabled, people can access the VoIP service over a wireless LAN. Calls to other wireless users are then free, but only if they are also Barablu members.
Currently, both the Nokia 9500 and i-mate SP5 and SP5m phones are compatible. You just need to download a dialer to your mobile and get registered. You can also make free calls to PCs or anything else you could do with a regular account from your mobile. You can make calls to non-Barablu users as well using the Barablu world account or receive calls from non-users, though there is obviously a fee for both services.