FastCall is optimized for Salesforce Sales Console.
From the Salesforce site:
Salesforce console is designed to boost productivity for users in fast-paced environments.
FastCall is optimized in Salesforce Console. Console allows users to easily drill into a Salesforce record opening many subtabs; something you cannot do on a standard Salesforce page. Console also allows FastCall users to edit a record while on a call. On a standard Salesforce page editing a record while on the softphone will end the call.
Salesforce Console is also very helpful when answering inbound phone calls. Without Console, an inbound call will pop a new browser tab. Console manages the Softphone inbound call search within the same workspace.
Note: Sales Console may need to be enabled in your org. Your Salesforce Account Executive can help you with a trial if not already enabled.
Once enabled, the steps to set up your Salesforce Console are described here on the Salesforce website. Console is a more advanced feature, and is highly personalized. FastCall assumes that you have reviewed the docs and will customize Console to your org. Once setup, FastCall is available in Console when the FastCall Call Center file is added.
Note The legacy Service Cloud Agent Console is not supported; FastCall is compatible with Salesforce Sales Console.