Download the softphone installer from the official website at the link. Install it by following the instructions of the installer.
After installation, run PhonerLite. Creating a new SIP account:
Go to "Configuration" -> "New"
Select "Manual Configuration"
In the "Domain/realm" field, enter the IP address of the MikoPBX you are going to connect to
Click the arrow to continue
In the "User name" field and in the "Authentication Name" field, enter the "Extension" of the employee from MikoPBX
In the "Password" field, enter the "SIP Password" from MikoPBX
Click the arrow to continue
Click on the check mark to continue
The green indicator at the bottom indicates successful authorization. Also, the status Online should be displayed on the PBX for this internal number.