To install and configure X-Lite softphone as an endpoint, follow the instructions:
First, download current X-Lite build here
Install X-Lite Softphone, follow instructions/screenshots:
Accept the terms and hit next
Choose settings then hit Next
On first Launch, choose Allow Access (this is from Windows 10).
Setup and Configure X-Lite
Go to Softphone -> Account Settings
Using your Team Member credentials, to find this go here
User ID = SEP Number
Domain = Proxy Server
Password = SEP Password
Click OK. DONE!