http://www.youfon.com only works for calling other users on the YouFon network. This is confirmed. I do not believe there is any way to call landlines or cell phones with it, however. Here is an example of what you would enter into Settings if you want to get it to work... Primary YouFon Number (YouFon Number1, i.e. parent a/c) 100000012106 (given to you when you register) Primary YouFon password: xxxxxxxx (given to you when you register) Reg Timout: 3600 Enable NAT?: YES STUN Domain: (BLANK) STUN SERVER: stun.youfon.net After that, just simply type in someone else's YouFon number and it will call them, one person will get a prompt asking to answer, and you can talk as much as you please!