We have a SIP softphone that is connected to an external Centrex loop-start line on an FXO port on a 2811. When the softphone generates DTMF digits, these digits are heard on the line so I know that RTP Named Telephony Events are being passed properly. Unfortunately, the SIP implementation on the 2811 does not relay the hookflash RTP event onto the FXO in order to get a 2nd dial-tone on the line to do conferencing, transfers, etc. I opened a TAC case but was told that this is not supported and was told to implement this feature using a TCL script running on the gateway.

I am new to writing TCL scripts on Cisco gateways. I have downloaded sample scripts from Cisco and I have the TCL IVR 2.0 Programming Guide. What I am looking for is how to trap RTP hookflash events in the TCL script so I can then use the (what I assume) sendhookflash command to generate a hookflash on the FXO port.