Business need to communicate with the customers over different CTI providers. May be they have Pre-existing licenses, commercials or for any other reason D365 need to be integrated to third party CTI service provider e.g. Genesys, Cisco etc.
To achieve this requirement Microsoft exposed Channel Integration Framework which has currently 2 versions. Having version 1.0 and 2.0 . Where V2.0 is good to leverage omnichannel feature. please refer below link for more information.
Please refer below link for the video guidance how to configure Channel Integration Framework(CIF) for Genesys & Cisco.