CTI is the abbreviation for Computer Telephony Integration and implies the combination of telecommunication with electronic data processing. Using SwyxIt! in a terminal server environment is only useful, if SwyxIt! is operated in CTI mode. CTI SwyxIt! on a terminal server can e.g. control a local SwyxIt! on another PC.
The CTI mode can be preset by the administrator. See also https://help.swyx.com/cpe/12.20/Administration/Swyx/en-US/index.html#context/Swyx_CTI_$.