For inbound calls you can specify to invoke either a visualforce page or a flow (Lightning only). The configuration is done in the SoftPhone Layout and it can be configured for
•No matching records (Caller ID is not found)
•Single-matching record (Contact, Account, Lead etc.) is found
•Multiple matching records (duplicate records are found)
The Visualforce page or flow is invoked using parameters where
•ANI = Caller ID
•DNIS = Called ID
•ID = record ID e.g. contact for single-matching record
•IVRID = ID typed in the IVR e.g. case number. Requires that ACD service is enabled.
For flows opening in existing tab as a pop-up, parameters may not be visible/accessible.