Develop a SIP cross-platform softphone compliant with Cisco Unified Communication Manager standards

We are planning to develop an application that allows the end user to use the softphone application deployed on the end-user machine to initiate the communication using Voice Over IP through the standard SIP protocol.

Description:
Develop a SIP cross-platform softphone compliant with Cisco Unified Communication Manager standards.

Scope:
1. Design the softphone UI/UX (logo and color scheme will be provided)
2. Covers all standard functionality for a SIP softphone.
3. Implement login (uses jwt) / logout
4. Supports click-to-call from websites.
5. Show a list of appointments with click to call
6. Update backend with call statistics
7. Show call history

Technical Requirements:
1. Cross-platform (Windows, Mac, Linux)
2. Use Linphone library
3. Use ElectronJs Framework with Javascript
4. Auto update to new versions
5. Does not require admin privileges
6. Portable App

Out of Scope:
1. Develop any backend API. All the below APIs will be provided with swagger files:
a. Login
b. Get Appointments
c. Get SIP Gateway Configuration
d. Store call statistics
2. Logo and color scheme will be provided.