Zoiper-free-3.15-setup.exe Verified -

Aesthetics: The interface is functional but looks dated. It resembles software from the Windows XP/7 era. It lacks the fluid animations and minimalist design of modern competitors like the redesigned Zoiper 5 or the Bria Solo.
Navigation: While dated, the layout is logical. The dial pad is prominent, and the contact list is easily accessible. For users who dislike "mystery meat" navigation (icons with no labels), Zoiper’s clearly labeled buttons are a welcome relief.

Cause: Missing Visual C++ Redistributables.
Fix: Download and install the latest Visual C++ Redistributable from Microsoft (both x86 and x64 versions).