CTIOS/Finesse Upgrade

We had a CTI client developed on CTIOS SDK, now our customer is planning to upgrade their system on latest platform and installing Cisco Finesse. Is there any changes we must do in our customized client to make that compatible with Cisco Finesse or its just another component working in parallel with CTIOS server?

I am assuming you would like to use both the clients?

Finesse connects to CTI Server and is a CTI Client.

CTI OS Server connects to CTI Server and is a CTI Client. 

The Client they have developed using CTI OS SDK connects to CTI OS server and doesn’t interfere with Finesse directly unless they are looking to use both clients to login agents

Can CTIOS server and Finesse server runs in parallel and by when CTIOS server will be discontinued?

Yes, they can run in parallel, even if CTIOS is disconnected.