Tragofone - White-label VoIP Softphone with WebRTC and Auto-provisioning
Layers - A simple Wordpress site builder & its free forever
PhonerLite - PhonerLite enables your PC to use it for internet telephony (VoIP , Voice over IP, SIP).
OnePager - One page theme builder for WordPress
tSIP - tomeko.net/software: SIP client for Windows.
Elementor - Elementor is a front-end drag & drop page builder for WordPress.