3CX Client for Windows is a freeware softphone application.
Here are some screenshots to illustrate the features and user interface of this application:
3CX Client for Windows: VOIP Phone. Screenshot of 3CX Client for Windows - 1528px · 1451px3CX Client for Windows: VoIP Phone. Screenshot of 3CX Client for Windows - 1510px · 1450px3CX Client for Windows: VOIP Phone. Screenshot of 3CX Client for Windows - 1539px · 1453px