Have you read the post from Ivann (that i have forwarded on her behalf) : the server is communicating with a modem too.
So it is like a MS-MS call. What happens when a MS sends a DTMF to another MS…? Why would there even be TFO ? Are the three requests polluting the DTMF tones ?
I found some Alcatel-Lucent fault reports about TFO and DTMF, but i don’t know if it’s related to this issue exactly.