IPICS supports PTT between IP Phones but also extend that to actual RF radios (Used by Police, Fire & Security personnel) as well as PSTN users (Users dialing from land/mobile lines) and PC/iPhone Clients. IPICS does a lot more than just PTT, it supports massive notifications and is typically used by Safety and Security departments:
Cisco IP Interoperability and Collaboration System (IPICS) is a complete IP-based dispatch and incidence response solution loaded with capabilities.
It provides an enhanced dispatch console, UHF/VHF radio interoperability, emergency first-responder notification, and integration with IP phones, cell phones, PCs, and mobile devices.
There is no direct integration between Barbee Informcast and Cisco IPICS however each IPICS channel is assigned a specific multicast IP address with a specific port number which can be shared over the same multicast domain with a Barbee Informcast channel that is assigned to a certain paging group. IPICS is typically two way communications and Paging by Barbee is just one way for the most part.