First download the Linphone Windows Desktop version on the Linphone website.

Install it with Cisco's OpenH264 codec:

 

Launch linphone (and accept the firewall rule):

 

 

Then click on "use sip account":

 

Put your SIP username on Username (Display name can be anything), On SIP domain put "sip.voice.boxis.net" (without the quote), and your password, transport must be udp, then click use:

 

Click on the linphone at the top left:

 

 

And then Select your account:

 

 

Click "OK", your Linphone is ready to accept call.