UTM 9 & Fritz!Box 7390 VoIP

Hello,

I tried the following config:

- ADSL with 1+1 --> DLINK Modem --> UTM = this works fine
- DMZ with Fritz!Box 7390 because of the VoIP to ISDN Phones
- FB configured Internet over LAN1 = works but the VoIP Accounts won´t register

- in the UTM I have a Masquarading Rule DMZ -> WAN
- and a Firewall Rule DMZ allow any Traffic to WAN

Did anyone tried this setup? Or just to run a FB because of the VoIP Phones?

Thanks

Frank