DTMF detection in a conference

Hi,

ich search since 3 days to solve my problem.

Ich want to start a AGI script by pressing the * digit on the Telephon while the caller is in a conference.

With features.conf and dial a local channel this is possible and my AGI script starts and i can handle a DTMF menu over the script and make some database operations.

But to call a local channel, for features.conf is not a fine solution i think.

I search a way to start the agi script by pressing the * digit without call a local channel.

thanks

sephi