> can you please tell me how to modify the TCL with the commands.
See http://www.cisco.com for documentation about the Cisco TCL IVR. Basically you should replace the default call application, which does not limit the call duration with either one of:
1) A TCL script which will do call authorization in the billing, and will disconnect the call after the h323-credit-time received from the billing
2) A TCL script which will have hardcoded “maximum call length 30 miniutes” in it
For the “1)” option – search google for “advanced remote authenticate tcl”