H.245 tunneling is used in conjunction with Fast Connect and consists of encapsulating H.245 messages in H.225 packets. It eliminates the need for a separate H.245 connection during call setup.
Check out the following for information on H.245 tunneling and how to configure:
http://www.cisco.com/univercd/cc/td/doc/product/access/acs_serv/as5400/sw_conf/ios_121/pullv2p2.htm
