Invision - Prototyping and collaboration for design teams
Tragofone - White-label VoIP Softphone with WebRTC and Auto-provisioning
MockupCreator - MockupCreator is a tool to create mockups, prototypes and wireframes.
PhonerLite - PhonerLite enables your PC to use it for internet telephony (VoIP , Voice over IP, SIP).
Amplitude - Mobile analytics: come with questions, leave with answers
tSIP - tomeko.net/software: SIP client for Windows.