1) Start by reading the CTI Server Protocol reference CTI Server Message Reference Guide (Protocol Version 13) for ICM Enterprise and Hosted Editions , which provides details about what CTI Server Protocol.
2) Next, download the C-API itself which includes a zip file with a C-API Reference and C++ project for the C-API including header and C files and a few examples such as makecall.
Note that all customers and partners wishing to deploy custom CTI integrations using C-API are required to have a valid Developer Services contract. For furtner information see Contact Center Developer Support Services requirement.
UCCE Design GuidesA good starting point if you are new to Contact Center is the UCCE Design Guides.UCCE Design Guides
Recommended training includes the following courses. These courses are introductory and provide a general understanding of system architecture and application development requirements. Though not focused entirely on UCCE application development using CTI Server C-API, these courses provide details that are important to developing for and supporting a UCCE system.