Tragofone - White-label VoIP Softphone with WebRTC and Auto-provisioning
ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
PhonerLite - PhonerLite enables your PC to use it for internet telephony (VoIP , Voice over IP, SIP).
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
tSIP - tomeko.net/software: SIP client for Windows.
LightShot - The fastest way to take a customizable screenshot.