The problem is not on the FXO ports because now we are using a VG224 with FXS port that is connected on the same network that IP phone. The FXO ports on the router 2851 are not yet used.

our problem is that the analog phone which is connected on the FXS port can call the IP phone which is connected on the lan; but when we want to redial the number of analog phone nothing pass.

we have a tonality of busy on the IP phone.

That we are waiting is the configuration which is adapted with this solution to know call analog phone which is connected on VG224 with ip phone.