IP address of the phone system
CSTA - User name and Password this user will need access to the all the extensions for UC Server.
Trusted Applications/IP's can be setup to replace the need for CSTA username and Password.
CSTA XML (CSTA323)
OpenScape Voice is a native SIP-based system scalable up to 100,000 users per system. It can be deployed on premise, in a data center (as a private cloud), it also can be multi-tenant hosted/public cloud solution.