I coded up this simple SIP engine and video phone a few years ago. I realized how easy it is to speak SIP without a lot of classes or abstraction. It is just plain-english SIP. The SIP is copy-pasted from wireshark, and then just does replace of whatever characters need to be changed to make or answer a specific call. I don't program much VOIP any more, and pretty soon I might have thrown away all my hard drives with this code on it. So I figured I would put my work somewhere in case...