Twinkle is a softphone for your voice over IP and instant messaging communications using the SIP protocol. You can use it for direct IP phone to IP phone communication or in a network using a SIP proxy to route your calls and messages.

In addition to making basic voice calls, Twinkle provides you the following features:

Hamachi is a handy tool that allows you to connect computers over the Internet and create your own virtual private network (VPN), protected with standard encryption algorithms, as if they were connected by the same physical local area network.