You would have to install the Softphone (which is an option in the User Apps install, not installed by default), create a Managed Phone for each softphone (see directions in the Help...involves the FQDN of the laptop). That station created for the softphone needs a Basic Station License. Also, the Softphone has to be provisioned to work properly, so set up DHCP as appropriate.
Then, when the agent logs into IC, they have to select SIP Soft Phone as the station type.