Open the Linphone app on your phone.
Click on the top icon on the top left that says "Assistant"
This assistant will help you configure and use your SIP account. Select the "Use SIP Account" option.
Username: From Voxtelesys
Password: From Voxtelesys
Domain: From Voxtelesys
Display Name: Name of user
After filling out the SIP settings, click on "Login"
Once the Green radio button says connected you can start making and receiving calls!