TCCS means Transparent Common Channel Signaling .
Transparent CCS allows the connection of two PBXs with digital interfaces that use a proprietary or unsupported CCS protocol without the need for interpretation of CCS signaling for call processing. T1/E1 traffic is transported transparently through the data network and the feature preserves proprietary signaling. From the PBX standpoint, this is accomplished through a point-to-point connection. Calls from the PBXs are not routed, but follow a preconfigured route to the destination.
Refer the following url for more information,
http://www.cisco.com/en/US/products/sw/iosswrel/ps1834/products_feature_guide09186a00800e9761.html
