Tragofone - White-label VoIP Softphone with WebRTC and Auto-provisioning
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
PhonerLite - PhonerLite enables your PC to use it for internet telephony (VoIP , Voice over IP, SIP).
Adobe XD - Adobe XD is an all-in-one UX/UI solution for designing websites, mobile apps and more.
tSIP - tomeko.net/software: SIP client for Windows.
UXpin - Design is really about solving problems. UXPin is the UX Design Platform that gets that right.