When Zoiper cannot display the preview of the camera and there is a "broken image" icon on the top right corner of the preview window, it's most probably issue caused by Zoiper not being able to connect with the localhost of the machine, caused by Antivirus or firewall which is blocking the connection.
Currently known to cause such issues are Eset Nod32 and Eset Internet Security.
In case of Eset NOD32 antivirus or Internet Security, please do the following :
- Go to Setup
- Configure Real time file system protection
- WEB and Email
- Edit Excluded application
- Add -> Browse button -> Add Zoiper5.exe to the list